So Rengar is just OP right now. He can be played (obviously) jungle, but also destroy's people toplane, and is a very strong kill lane support. 90% of this is because his REDICULOUS passive has NO COOLDOWN. He can just freely hop in and out of bushes whenever he feels like it. Literally all Riot have to do to tone him down is just put a cooldown on the jump. 10 seconds seems completely reasonable for ganking (to keep him in the jungle _where he belongs_).