I'm not a "pro" in any way, shape, or form, but I can say that I feel 100% certain of the way to build and play this hero, and I see it being done incorrectly so many times. I'm going to make this short and sweet. This is not intended for the newest of new players so I therefore will not explain the most basic concepts such as jungling or creep pulling.
Explanation of skill build:
Most people choose to optimize whirling blade before Taunt. In team games with good coordination, this is absolutely incorrect. Not even counting other teammates who may be in the lane, assuming you spin on average once every second, at level 7 with rank 4 taunt and rank 2 whirling blade you will spin 3 times for 3x125 = 375 damage. Assuming you had rank 4 whirling blade and rank 2 taunt you would spin twice for 2x175=350 damage. You actually gain damage in all but the most extreme cases where you spin every time the cooldown is refreshed. Now also account for the fact that the extra second allows 1 or 2 other laning heroes to deal extra damage, as well as an extra second where the opposing hero can not retaliate.
Terrify is garbage against anyone but the newest players. It will be removed within 5 seconds. Late game, the damage is nearly out regened. Stats are very important for your mana pool so you can blink>taunt>ult with ease.
1. Iron buckler (whatever the new one is called)
2. 6x Runes of the blight
Axe should be bottom lane legion or top lane hellbourne. You should be jungling and creep pulling when possible, and coming out of the woods to gank. Also, a lot of people seem to like the whole "go behind the tower and tank creeps." This has never worked against a well played ranged hero. You will be sent back to base within a minute. It can, however, be viable against a double melee lane (aka pubs) if you do it properly.
Helm of the victim (NOT black legion)
Finish Shaman's Headdress
Notice how I neglect to build helm of the black legion. Personal preference. I feel the regen with Shaman's headdress and helm of the black legion to be superfluous. Most of this is self explanatory. The legion helm will make jungling a breeze with the armor and regeneration it provides. The portal key is for ganking and initiation. The null is there to support your combo, and the post haste boots are to help you push.
This point is where most of the guides differ. Some argue behemoth heart, others blademail. To be honest you can't go wrong, though I do disagree with the blademail. So much damage is mitigated by axe that hardly any gets returned... it's counter productive.
What do I do? It definiately depends on the team. If you still find yourself getting nuked hard from the casters during your taunt, you might want a shrunken head. In most cases, I get a Frostfield Plate (Shva's Guard)
It provides much needed armor to increase your effective hit points, mana so you can repeatedly blink> taunt> activate plate, and the snare is amazing following a taunt or for escaping. It might seem silly to get a +25intel item on a strength hero, but just try it, you won't be dissapointed.
Hope this helps, and as always, I'm open for criticism.