^Wrong, I watched PhantomL0rd play AP Rengar a while ago on stream like he does with every new champ with an AP scaling.
He said that there's no way in hell AP Rengar is gonna work. His W, the only AP scale, has too long CD and the heal is too weak to rely on.
Also, Rengar has crazy burst at lvl 1 because his regular and empowered abilities don't share the same cooldown. That means if you have 4 Ferocity stacks and attack someone with Q you can use it immediately for an empowered Q dealing over 50% health of the enemy in less than 1 second.