Togashi
11-26-2009, 07:10 PM
This is my first guide, I copied and pasted from a Maliken guide that I liked the format of. Feel free to give me tips for improvement. This guide is primarily for EM, although there is always some rollover between easy and normal mode.
http://i121.photobucket.com/albums/o224/Choebob/Engineer.jpg
Introduction
Engineer is a ranged agility hero. With the correct equipment he carries very well. Naturally his is pretty supportive and can even limitedly tank. He's an all-around character that can fill multiple roles and has some pretty good utility.
Skills
http://i121.photobucket.com/albums/o224/Choebob/TheKeg.jpg
The Keg is Engineer's ranged aoe stun and knockback. It has some really good uses including, but not limited to: initiating, seperating enemies, escaping, and last hitting. Be careful though, it has some cast time, so be sure to anticipate the movements of your enemies, like with Pyromancer's Dragonfire.
http://i121.photobucket.com/albums/o224/Choebob/SteamTurret.jpg
Steam Turret is possibly his best skill, imho. Placed correctly and timed right, it will demolish heros by itself. Tinkering it only adds insult to injury. Dropping this, ulting, and tinkering the turret can net you 1-2 kills solo or even more in group fights. The mechanic that makes this ability ridiculous is the fact that it takes on your gear. While I build defense items early which don't help the turret, your mid-late game items make this guy a monster.
http://i121.photobucket.com/albums/o224/Choebob/Tinker.jpg
Tinker is utility at it's best. Why have an ability that can do one thing when you have one that can do four things? The best abilities by far are the ability to boost your ult and your turret. But don't underrate boosting a tower when your enemy is creep blocked while pushing, or boosting your catapult when your pushing or your turret is on cooldown. I don't really use to to debuff enemy units, but I imagine it's not bad.
http://i121.photobucket.com/albums/o224/Choebob/EnergyField.jpg
Energy Field is a great asset in team battles. It deals damage based on max health (so whether you hit tanks or squishies it's gonna hurt them. If they stay in at rank 3 for the duration they lose 64% of their health (taking into account base magic armor), and if you tinker it they have to heal or die (102%). If they decide to run, well they get slowed and silenced, allowing your team to chase. If you have this up and your turret set inside, watch them fall.
Skill Builds
Solo build
1. Steam Turret
2. The Keg
3. Steam Turret
4. Tinker
5. Steam Turret
6. The Keg
7. Steam Turret
8. The Keg
9. The Keg
10. Energy Field
11. Energy Field
12-14. Tinker
15. Stats
16. Energy Field
17+ Stats
Laning build
1. Steam Turret
2. The Keg
3. Steam Turret
4. The Keg
5. Steam Turret
6.The Keg
7. Steam Turret
8. The Keg
9. Tinker/Stats
10. Energy Field
11. Energy Field
12-14. Tinker
15. Stats
16. Energy Field
17+ Stats
In the solo build, you opt for Steam Turret before The Keg and get an early level of Tinker as this will sometimes be the difference between who gets bloodlusted in the middle lane. I will post good turret positions for the middle lane further into the guide.
In the laning build you get Steam Turret early and post it as a river ward. At level 1, most ranged heroes attack extremely slowly (~1 attack every 2 seconds) This means it will take someone 10 seconds to smash your turret, in which time your turret will use up all its mana doing about 680 damage. Thus, no one in their right minds will attempt to take it down. Once you hit level 3, you can start using your Turret to harass / farm in the lane.
Item Builds
Basic Starting Items
http://honwiki.net/w/images/0/09/Runes_of_the_Blightitem.gifx2
http://honwiki.net/w/images/e/e5/Mana_Potionitem.gifx3
http://honwiki.net/w/images/0/05/Iron_Buckleritem.gif
http://honwiki.net/w/images/b/bb/Minor_Totemitem.gifx2
http://honwiki.net/w/images/e/ec/Monkey_Courieritem.gif
Runes of Blight x2 = 180g
Mana Potion x2 = 100g
Minor Totem x2 = 106g
Monkey Courier = 200g
Total = 586g
This is the basic starting items I buy for Engineer, it's not set in stone, but this is very effective in maintaining your health and mana. The shield is just to protect you from being harassed by 600 range heros and to build into helm later.
Core items
http://honwiki.net/w/images/7/7d/Marchersitem.gifhttp://honwiki.net/w/images/4/45/Punch_Daggeritem.gifhttp://honwiki.net/w/images/4/45/Punch_Daggeritem.gif-->http://honwiki.net/w/images/1/10/Enhanced_Marchersitem.gif
Marchers = 500g
Punchdagger x2 = 1000g
Total = 1500g
http://honwiki.net/w/images/6/67/Mana_Batteryitem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/f/fd/Power_Supplyitem.gif
Mana Battery = 210g
Power Supply Recipe = 203g
Total = 413g
http://honwiki.net/w/images/0/07/Warhammeritem.gifhttp://honwiki.net/w/images/a/a0/Gloves_of_the_Swiftitem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/7/7b/Thunder_Clawitem.gif (http://honwiki.net/w/images/7/7b/Thunder_Clawitem.gif)
Warhammer = 1600g
Gloves of the Swift = 500g
Thunder Claw Recipe = 900g
Total = 3000g
http://honwiki.net/w/images/3/3a/Mighty_Bladeitem.gifhttp://honwiki.net/w/images/0/07/Warhammeritem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/a/a4/Shrunken_Headitem.gif
Mighty Blade = 1000g
Warhammer = 1600g
Shrunken Head Recipe = 1300g
Total = 3900g
This is the goal, I can generally farm this within the first 30 minutes of the game, and while I am listing this as core items it's only because the next items you buy are pretty variable. I would buy these items in every game, pretty much every time. Ghost Marchers adds good damage to you and your turret, plus the creep walking is always useful. Power Supply gives a good mana fix for Engineer, and of course there's the whole "a fully charged Power Supply gives you more than a full Bottle" argument. Thunder Claw is just ridiculous. Adds damage, attack speed, and a good proc to both you and your turrets. There is really no reason to ever not get this item, in fact, rush it after Ghost Marchers and Power Supply. Lastly, Shrunken Head is necessary to stay alive in team fights most of the time. If you're feeling ballsy or have some great support, you can possibly skip it. I would not recommend it though.
*optional
http://honwiki.net/w/images/6/6e/Portal_Keyitem.gif
Portal Key = 2150g
Portal Key will help you set up some really good ults and turrets in team fights. A nice solid choice, and with the farming skills from Thunder Claw, not hard to scrape together the gold.
Luxury items
http://honwiki.net/w/images/2/2a/Warped_Cleftitem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/1/1c/Charged_Hammeritem.gif
Warpcleft = 2100g
Charged Hammer Recipe = 400g
Total = 2500g
http://honwiki.net/w/images/b/bb/Halberditem.gifhttp://honwiki.net/w/images/b/bb/Halberditem.gifhttp://honwiki.net/w/images/a/a3/Slayeritem.gif-->http://honwiki.net/w/images/7/79/Savage_Maceitem.gif
Halberd = 1500g
Halberd = 1500g
Slayer = 2400g
Total = 5400g
http://honwiki.net/w/images/5/51/Quick_Bladeitem.gifhttp://honwiki.net/w/images/5/51/Quick_Bladeitem.gifhttp://honwiki.net/w/images/0/0b/Apprentice%27s_Robeitem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/c/c5/Nullfire_Bladeitem.gif (http://honwiki.net/w/images/c/c5/Nullfire_Bladeitem.gif)
Quick Blade = 1000g
Quick Blade = 1000g
Apprentice's Robe = 450g
Nullfire Blade Recipe = 850g
Total = 3300g
http://honwiki.net/w/images/0/05/Iron_Buckleritem.gifhttp://honwiki.net/w/images/d/de/Lifetubeitem.gifhttp://honwiki.net/w/images/6/60/Beast_Heartitem.gif-->http://honwiki.net/w/images/f/f4/Helm_of_the_Black_Legionitem.gif
Iron Buckler = 250g
Lifetube = 875g
Beastheart = 1100g
Total = 2225g
Looking at all of these items, it's a large amount to ask anyone to farm, but you don't really need all of these to finish a game. Most of the time you'll opt for one and the game is over before you finish it, unless you're playing EM. They're more or less listed in order of importance. Charged Hammer is a natural way to go with your completed Thunder Claw. Savage Mace makes it next to impossible for enemies to channel with you and your turret around. Nullfire Blade adds a lot of mana burn to your turret and yourself. It's a good boost to damage and can really screw up your opponent, and the purge can really help against a lot of heroes. Helm of the Black Legion is a situational defensive item. I like it because I tend to initiate with Engineer in the mid game so this helps mitigate a bit of damage. To each their own I guess.
Why not...
http://honwiki.net/w/images/2/2d/Mock_of_Brillianceitem.gif
Mock of Brilliance
Mock of Brilliance does add some damage, will let your turret solo the monkey man, and doubles up when you and your turret are standing together, but the benefits just don't compare to Savage Mace and Charged Hammer which are the only other luxury items of similar cost.
http://honwiki.net/w/images/4/44/Wingbowitem.gif
Wingbow
Wingbow may seem like a great item for Engineer, and it's certainly not bad. But like Mock of Brilliance the benefits don't outweigh the cost. Agi and evasion (not positive about evasion) add nothing to your turret, so it really just says +30 damage and attack speed for 6000g to your turret. You really shouldn't need the evasion (between Shrunken Head and ghost tactics, you shouldn't be focussed too badly) the rest are great benefits, but again, 6000g is just too much when you can finish your Charged Hammer and some of your Savage Mace for the same price.
Early game
Choosing a solo or dual lane
I prefer to run Engineer solo in mid because he has a very strong presence and is fairly difficult to harass. At the same time though, don't be afraid to give mid to Soulstealer or TB because Engineer adds a lot to a lane. With his stun and his additional attacker, he can make it hard for the opposing pair to deal with your lane.
Early solo laning
Obviously last hitting is important with any hero, not more so with Engineer for any reason, but pretty easy. Once you set up your turret you'll be getting a lot of last hits, make sure that after a wave when your turret is out of mana you put him to rest while the next wave makes its way down. If your opponent is being particularly brave and moves close to harass, set down the turret and target it on him, it'll bring him down fast in the early game and if he runs, throw a keg in front of him, that's how you get the bloodlust. I've found that often times a side lane hero will come to try and help mid gank you, but all you have to do is stay near your tower and if they get to close, keg them and run. Pretty simple.
Dual laning
Coming soon...
Item progression
You generally want to finish your Power Supply and Ghost Marchers. If your early game is going well, start on Thunder Claw as well.
Early game TPs, counter ganks, ganks
Always come from the forrest, open with a keg to knock them closer to your team, then rush in and drop your ult and a turret. If they try to fight it out, just tinker your turret and they should go down, but make sure not to bother if they run because you'll just be wasting time you could be chasing. The slow is only 2 seconds so you gotta be on their ass to make sure you get the kill.
Map awareness
Not the most important thing because you're a pretty tough agility hero, but don't let yourself get cocky. The worst thing would be to keg and run from two heroes only to have the 3rd come from the forrest halfway down the lane to hold you for the others.
Early game weakness
While I wouldn't say that Engineer is weak in the early game, but you're not likely to get bloodlust unless your opponents are playing too aggressive. The early game with Engineer is all about a strong defense, so strong in fact that it'll kill people who are too offensive.
Mid game
Item progression
Finish Thunder Claw as soon as possible. After that, you should probably start on Shrunken Head and Portal Key. You could instead finish your Charged Hammer if you're not worried about mid game ganks against you, but be cautious.
Mid game strength
In the mid game Engineer's strength is in team fights. Yes you can probably solo some heroes, but your ult is best used on a group. So this is a great time to rake in the assists. If your tank isn't up to par yet or is just too far away and it's 4v3 or something, don't be afraid to initiate. With your boots, helm, and aoe abilities there's a good chance you're going to send them running before they get a chance to kill you, and hopefully your team can get a kill or two in the process.
Team fights, when and how
Always face off on at least even ground (3v3, 4v4, etc) and again, don't be afraid to initiate if you have to. The cooldown on The Keg is short enough that you should be able to open with it and have it up again to knock one or more back to you if they try to run in the end. Aiming is key.
End game
Engineer's strong point
At this point you're equiped with a strong set of abilities and gear that not only benefits you, but your turret as well. It's like having a really strong but defensively weak version of yourself to come along with you. If you go with Savage Mace after the Nullfireblade then when you and your turret are in the fray, people's mana disappear and their channel spells rarely take full effect. This is the time where you will probably get most of your killing blows (unless you manipulated using The Keg in the mid game to get the KB's).
In depth team fights
Coming soon...
Farming
If you feel you really need more gear to tear people appart, stack creeps in the ancient camps and then hold them while your turret tears them to shreds. Just make sure you stay in front of the turret because once they switch to it, they're not coming back to you until it's dead.
Ganking
You should definitely be able to solo kill most heroes now. Run in, drop turret, tinker, and when they try to run, keg them. Easy kills. The most trouble you'll see is anyone who can stun lock you. So avoid those people if you see them (Chronos, Madman with basher, Panda, etc.)
Item progression, X vs Y items
Coming soon...
Update 11/26/09: changed Energy Field values to include base magic armor
Update 11/27/09: changed luxury items to include shrunken head
Update 11/28/09: edited luxury items to include frostwolf skull and shieldbreaker, downplayed mock
Update 11/29/09: revamped item section
Update 12/01/09: switched around some items
Update 12/02/09: switched more items around and added some new ones, changed skill builds slightly
http://i121.photobucket.com/albums/o224/Choebob/Engineer.jpg
Introduction
Engineer is a ranged agility hero. With the correct equipment he carries very well. Naturally his is pretty supportive and can even limitedly tank. He's an all-around character that can fill multiple roles and has some pretty good utility.
Skills
http://i121.photobucket.com/albums/o224/Choebob/TheKeg.jpg
The Keg is Engineer's ranged aoe stun and knockback. It has some really good uses including, but not limited to: initiating, seperating enemies, escaping, and last hitting. Be careful though, it has some cast time, so be sure to anticipate the movements of your enemies, like with Pyromancer's Dragonfire.
http://i121.photobucket.com/albums/o224/Choebob/SteamTurret.jpg
Steam Turret is possibly his best skill, imho. Placed correctly and timed right, it will demolish heros by itself. Tinkering it only adds insult to injury. Dropping this, ulting, and tinkering the turret can net you 1-2 kills solo or even more in group fights. The mechanic that makes this ability ridiculous is the fact that it takes on your gear. While I build defense items early which don't help the turret, your mid-late game items make this guy a monster.
http://i121.photobucket.com/albums/o224/Choebob/Tinker.jpg
Tinker is utility at it's best. Why have an ability that can do one thing when you have one that can do four things? The best abilities by far are the ability to boost your ult and your turret. But don't underrate boosting a tower when your enemy is creep blocked while pushing, or boosting your catapult when your pushing or your turret is on cooldown. I don't really use to to debuff enemy units, but I imagine it's not bad.
http://i121.photobucket.com/albums/o224/Choebob/EnergyField.jpg
Energy Field is a great asset in team battles. It deals damage based on max health (so whether you hit tanks or squishies it's gonna hurt them. If they stay in at rank 3 for the duration they lose 64% of their health (taking into account base magic armor), and if you tinker it they have to heal or die (102%). If they decide to run, well they get slowed and silenced, allowing your team to chase. If you have this up and your turret set inside, watch them fall.
Skill Builds
Solo build
1. Steam Turret
2. The Keg
3. Steam Turret
4. Tinker
5. Steam Turret
6. The Keg
7. Steam Turret
8. The Keg
9. The Keg
10. Energy Field
11. Energy Field
12-14. Tinker
15. Stats
16. Energy Field
17+ Stats
Laning build
1. Steam Turret
2. The Keg
3. Steam Turret
4. The Keg
5. Steam Turret
6.The Keg
7. Steam Turret
8. The Keg
9. Tinker/Stats
10. Energy Field
11. Energy Field
12-14. Tinker
15. Stats
16. Energy Field
17+ Stats
In the solo build, you opt for Steam Turret before The Keg and get an early level of Tinker as this will sometimes be the difference between who gets bloodlusted in the middle lane. I will post good turret positions for the middle lane further into the guide.
In the laning build you get Steam Turret early and post it as a river ward. At level 1, most ranged heroes attack extremely slowly (~1 attack every 2 seconds) This means it will take someone 10 seconds to smash your turret, in which time your turret will use up all its mana doing about 680 damage. Thus, no one in their right minds will attempt to take it down. Once you hit level 3, you can start using your Turret to harass / farm in the lane.
Item Builds
Basic Starting Items
http://honwiki.net/w/images/0/09/Runes_of_the_Blightitem.gifx2
http://honwiki.net/w/images/e/e5/Mana_Potionitem.gifx3
http://honwiki.net/w/images/0/05/Iron_Buckleritem.gif
http://honwiki.net/w/images/b/bb/Minor_Totemitem.gifx2
http://honwiki.net/w/images/e/ec/Monkey_Courieritem.gif
Runes of Blight x2 = 180g
Mana Potion x2 = 100g
Minor Totem x2 = 106g
Monkey Courier = 200g
Total = 586g
This is the basic starting items I buy for Engineer, it's not set in stone, but this is very effective in maintaining your health and mana. The shield is just to protect you from being harassed by 600 range heros and to build into helm later.
Core items
http://honwiki.net/w/images/7/7d/Marchersitem.gifhttp://honwiki.net/w/images/4/45/Punch_Daggeritem.gifhttp://honwiki.net/w/images/4/45/Punch_Daggeritem.gif-->http://honwiki.net/w/images/1/10/Enhanced_Marchersitem.gif
Marchers = 500g
Punchdagger x2 = 1000g
Total = 1500g
http://honwiki.net/w/images/6/67/Mana_Batteryitem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/f/fd/Power_Supplyitem.gif
Mana Battery = 210g
Power Supply Recipe = 203g
Total = 413g
http://honwiki.net/w/images/0/07/Warhammeritem.gifhttp://honwiki.net/w/images/a/a0/Gloves_of_the_Swiftitem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/7/7b/Thunder_Clawitem.gif (http://honwiki.net/w/images/7/7b/Thunder_Clawitem.gif)
Warhammer = 1600g
Gloves of the Swift = 500g
Thunder Claw Recipe = 900g
Total = 3000g
http://honwiki.net/w/images/3/3a/Mighty_Bladeitem.gifhttp://honwiki.net/w/images/0/07/Warhammeritem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/a/a4/Shrunken_Headitem.gif
Mighty Blade = 1000g
Warhammer = 1600g
Shrunken Head Recipe = 1300g
Total = 3900g
This is the goal, I can generally farm this within the first 30 minutes of the game, and while I am listing this as core items it's only because the next items you buy are pretty variable. I would buy these items in every game, pretty much every time. Ghost Marchers adds good damage to you and your turret, plus the creep walking is always useful. Power Supply gives a good mana fix for Engineer, and of course there's the whole "a fully charged Power Supply gives you more than a full Bottle" argument. Thunder Claw is just ridiculous. Adds damage, attack speed, and a good proc to both you and your turrets. There is really no reason to ever not get this item, in fact, rush it after Ghost Marchers and Power Supply. Lastly, Shrunken Head is necessary to stay alive in team fights most of the time. If you're feeling ballsy or have some great support, you can possibly skip it. I would not recommend it though.
*optional
http://honwiki.net/w/images/6/6e/Portal_Keyitem.gif
Portal Key = 2150g
Portal Key will help you set up some really good ults and turrets in team fights. A nice solid choice, and with the farming skills from Thunder Claw, not hard to scrape together the gold.
Luxury items
http://honwiki.net/w/images/2/2a/Warped_Cleftitem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/1/1c/Charged_Hammeritem.gif
Warpcleft = 2100g
Charged Hammer Recipe = 400g
Total = 2500g
http://honwiki.net/w/images/b/bb/Halberditem.gifhttp://honwiki.net/w/images/b/bb/Halberditem.gifhttp://honwiki.net/w/images/a/a3/Slayeritem.gif-->http://honwiki.net/w/images/7/79/Savage_Maceitem.gif
Halberd = 1500g
Halberd = 1500g
Slayer = 2400g
Total = 5400g
http://honwiki.net/w/images/5/51/Quick_Bladeitem.gifhttp://honwiki.net/w/images/5/51/Quick_Bladeitem.gifhttp://honwiki.net/w/images/0/0b/Apprentice%27s_Robeitem.gifhttp://honwiki.net/w/images/7/72/Recipe.gif-->http://honwiki.net/w/images/c/c5/Nullfire_Bladeitem.gif (http://honwiki.net/w/images/c/c5/Nullfire_Bladeitem.gif)
Quick Blade = 1000g
Quick Blade = 1000g
Apprentice's Robe = 450g
Nullfire Blade Recipe = 850g
Total = 3300g
http://honwiki.net/w/images/0/05/Iron_Buckleritem.gifhttp://honwiki.net/w/images/d/de/Lifetubeitem.gifhttp://honwiki.net/w/images/6/60/Beast_Heartitem.gif-->http://honwiki.net/w/images/f/f4/Helm_of_the_Black_Legionitem.gif
Iron Buckler = 250g
Lifetube = 875g
Beastheart = 1100g
Total = 2225g
Looking at all of these items, it's a large amount to ask anyone to farm, but you don't really need all of these to finish a game. Most of the time you'll opt for one and the game is over before you finish it, unless you're playing EM. They're more or less listed in order of importance. Charged Hammer is a natural way to go with your completed Thunder Claw. Savage Mace makes it next to impossible for enemies to channel with you and your turret around. Nullfire Blade adds a lot of mana burn to your turret and yourself. It's a good boost to damage and can really screw up your opponent, and the purge can really help against a lot of heroes. Helm of the Black Legion is a situational defensive item. I like it because I tend to initiate with Engineer in the mid game so this helps mitigate a bit of damage. To each their own I guess.
Why not...
http://honwiki.net/w/images/2/2d/Mock_of_Brillianceitem.gif
Mock of Brilliance
Mock of Brilliance does add some damage, will let your turret solo the monkey man, and doubles up when you and your turret are standing together, but the benefits just don't compare to Savage Mace and Charged Hammer which are the only other luxury items of similar cost.
http://honwiki.net/w/images/4/44/Wingbowitem.gif
Wingbow
Wingbow may seem like a great item for Engineer, and it's certainly not bad. But like Mock of Brilliance the benefits don't outweigh the cost. Agi and evasion (not positive about evasion) add nothing to your turret, so it really just says +30 damage and attack speed for 6000g to your turret. You really shouldn't need the evasion (between Shrunken Head and ghost tactics, you shouldn't be focussed too badly) the rest are great benefits, but again, 6000g is just too much when you can finish your Charged Hammer and some of your Savage Mace for the same price.
Early game
Choosing a solo or dual lane
I prefer to run Engineer solo in mid because he has a very strong presence and is fairly difficult to harass. At the same time though, don't be afraid to give mid to Soulstealer or TB because Engineer adds a lot to a lane. With his stun and his additional attacker, he can make it hard for the opposing pair to deal with your lane.
Early solo laning
Obviously last hitting is important with any hero, not more so with Engineer for any reason, but pretty easy. Once you set up your turret you'll be getting a lot of last hits, make sure that after a wave when your turret is out of mana you put him to rest while the next wave makes its way down. If your opponent is being particularly brave and moves close to harass, set down the turret and target it on him, it'll bring him down fast in the early game and if he runs, throw a keg in front of him, that's how you get the bloodlust. I've found that often times a side lane hero will come to try and help mid gank you, but all you have to do is stay near your tower and if they get to close, keg them and run. Pretty simple.
Dual laning
Coming soon...
Item progression
You generally want to finish your Power Supply and Ghost Marchers. If your early game is going well, start on Thunder Claw as well.
Early game TPs, counter ganks, ganks
Always come from the forrest, open with a keg to knock them closer to your team, then rush in and drop your ult and a turret. If they try to fight it out, just tinker your turret and they should go down, but make sure not to bother if they run because you'll just be wasting time you could be chasing. The slow is only 2 seconds so you gotta be on their ass to make sure you get the kill.
Map awareness
Not the most important thing because you're a pretty tough agility hero, but don't let yourself get cocky. The worst thing would be to keg and run from two heroes only to have the 3rd come from the forrest halfway down the lane to hold you for the others.
Early game weakness
While I wouldn't say that Engineer is weak in the early game, but you're not likely to get bloodlust unless your opponents are playing too aggressive. The early game with Engineer is all about a strong defense, so strong in fact that it'll kill people who are too offensive.
Mid game
Item progression
Finish Thunder Claw as soon as possible. After that, you should probably start on Shrunken Head and Portal Key. You could instead finish your Charged Hammer if you're not worried about mid game ganks against you, but be cautious.
Mid game strength
In the mid game Engineer's strength is in team fights. Yes you can probably solo some heroes, but your ult is best used on a group. So this is a great time to rake in the assists. If your tank isn't up to par yet or is just too far away and it's 4v3 or something, don't be afraid to initiate. With your boots, helm, and aoe abilities there's a good chance you're going to send them running before they get a chance to kill you, and hopefully your team can get a kill or two in the process.
Team fights, when and how
Always face off on at least even ground (3v3, 4v4, etc) and again, don't be afraid to initiate if you have to. The cooldown on The Keg is short enough that you should be able to open with it and have it up again to knock one or more back to you if they try to run in the end. Aiming is key.
End game
Engineer's strong point
At this point you're equiped with a strong set of abilities and gear that not only benefits you, but your turret as well. It's like having a really strong but defensively weak version of yourself to come along with you. If you go with Savage Mace after the Nullfireblade then when you and your turret are in the fray, people's mana disappear and their channel spells rarely take full effect. This is the time where you will probably get most of your killing blows (unless you manipulated using The Keg in the mid game to get the KB's).
In depth team fights
Coming soon...
Farming
If you feel you really need more gear to tear people appart, stack creeps in the ancient camps and then hold them while your turret tears them to shreds. Just make sure you stay in front of the turret because once they switch to it, they're not coming back to you until it's dead.
Ganking
You should definitely be able to solo kill most heroes now. Run in, drop turret, tinker, and when they try to run, keg them. Easy kills. The most trouble you'll see is anyone who can stun lock you. So avoid those people if you see them (Chronos, Madman with basher, Panda, etc.)
Item progression, X vs Y items
Coming soon...
Update 11/26/09: changed Energy Field values to include base magic armor
Update 11/27/09: changed luxury items to include shrunken head
Update 11/28/09: edited luxury items to include frostwolf skull and shieldbreaker, downplayed mock
Update 11/29/09: revamped item section
Update 12/01/09: switched around some items
Update 12/02/09: switched more items around and added some new ones, changed skill builds slightly