1. Make Crushing Blow do magical instead of physical damage, this is for a reason (see 2)
2. Change his ultimate to give him magic immunity for some amount of time instead of armor reduction.
Now, naturally you'll notice that if CB deals magical damage he can go immune and deal damage with it without being hurt. The magic immunity also greatly helps him, a pure melee hero without any inherent escape mechanism. His ult would be similar to Old N'aix ult or his Rage spell and we know how well N'aix works. Predator is currently a low tier hero and these small changes would change that quickly.
Also, fix the thing where after doing a poison leap Predator does not auto attack what he leaped to, instead smacking any nearby creeps first.
I tried poison leaping to friendlies earlier today and it didn't work, maybe you're thinking of pounce? If so it's still a greatly inferior escape mechanism when stacked against the escape mechanisms of the other big strength carries out there, Pestilence and Warbeast. Hammerstorm also lacks an escape mechanism but he has that great ranged stun to make up for it. If Predator leaps in to initiate and if he miscalculates (someone is hiding in the woods, ect) he is dead 100% of the time against good enemies while WB/Pesti/Hammerstorm all have a decent chance of escape, and as we all know the name of the game when it comes to carries is survival.
Changing his ulti makes him better all around which would be much appreciated on a bottom of the barrel hero. It would:
let him gank better (poison leap+a usable crushing blow while ulti is up)
let him carry earlier (free bkb on N'aix is what makes him so amazingly lethal midgame compared to other carries who have to buy one)
help him escape more often (throw up ulti now you can't be disabled, run to nearest tower or leap to creeps if that does indeed work)
Personally, I really love the predator model and I also love the hero concept, I just think it would be a lot better with a couple of small changes.
I don't even use Reckless Blow anymore. Takes up valuable points for Venomous Leap and Carnivorous, and later in the game my autoattack is more valuable than Reckless Blow, because Reckless Blow doesn't animate faster under your ult like the auto-attack does.
If anything, I'd replace Reckless Blow with a different skill altogether. Maybe something to emulate the Blaze (AoE blue fireball) ability from Savage 2, but something that synergizes more with him. Reckless Blow doesn't synergize in any way other than carnivorous healing the damage you took... if the enemy hasn't already outrun you due to the animation.
giving mass aoe silense to the ultimate, replacing armor reduction could be useful. this could make people to calculate their leaps to disable enemies by ult, not only turn on magic immunity (like old n'aix) and focus nearest low hp.
now bkb is a core item for predator, and i cant say that i like it.