So i just finished a game with zilean and some guy asked what the cooldown on chronoshift was. I just said 30 seconds randomly and actually started wondering myself

40% cooldown

Rewind 6s > 3.6 s
Chronoshift 180s > 108 s
8 * 10 = 80 (time rewinded after 8 uses)
and
3.6 * 8 = 28.8 seconds (time it takes to use 8 times)

--So max cd means ult every 30 seconds

If you already knew, lets talk about how cheap this is.

lol

Time Jesus yo

That's only if the Zilean
can afford the mana costs.
Has 40% CDR. DIdn't get focused/die within the 30 seconds.

Yes.

So it's not cheap.

The balance in this is the fact that to keep that up he has to have a loft of mana. It's surprising how rewind can sap you.