Unclean Beast
Right now, I don't think he is as interresting as the others: he is an excelent(spelling?) creep killer and a fast attacker but thats it.
Creeps are easy to be killed so he doesn't benefit a lot from that. The biggest thing imho is that you don't have alot of control:
He has a toggling ability, a power booster(Bestial wrath) and two direct attacks which are a bit boring. More synergizing between his skills would be cool.
-Ooze, I never take an high lvl ooze since it kills me, and the increase in creep killing isn't very usefull; he needs anti-demigod skills not creep slaughtering powers. Instead add an extra effect like slow or armor reduction(Pudge's Rot) to make it actually usefull on high lvl's.
-Venom spit: Doesnt do a lot of dmg and the range is too small. An increase in range would be cool, but another effect would be better. Like, the target leaves a slimy trail which heals UB and allies (and possible make them faster when walking on it) and slows and damages enemies. What this does is that when a enemy flees UB can get him.
-Bestial wrath: something special would be needed here.
-Grip: Not bad.
Plague: This is where all his skills should synergize with. Make the plague AIDS. Meaning that instead of dmg the enemy armor reduced, spell resitance is lowered, CD lowered, etc. Just making enemies weaker instead of killing them. Another thing would be cool is that, his other skills get additional effects when someone is plagued. Right now plague is just some creep killing ability, but with this change it would be the core of his skills.
P.S. His tongue should get something to do, please!