Zilean's passive is neigh unusable

In ranked 5's it's probably fine.

In your typical game of soloQ, even when you're supporting so you have constant access to an ally, it's really difficult to find an out of combat window long enough, where your ally is just the right amount of xp away from leveling up, so you can actually use his passive more than once or twice per game.

I love that I can see it doing something, but if I only get to see that effect once or twice per game, I'm a sad time wizard.

@riot, could you consider this QoL? Increase the amount of xp zilean gives, and lengthen the cooldown. Net power should be neutral, but it'll be hella easier to actually use it. Or if you're looking at actual buffs for the zil'sta, allowing him to use his passive in combat would be really nice.