Xerath Passive

Okay, first off, I know why his passive exists in the form it does. So he can have windows where he comes out from the backline to auto. It's very unsatisfying, though, how there is no true incentive to use this passive past when you get your morellonomicon. So here's a (couple of) suggestions!

First off, it has a static 12 second cooldown, where most champions nowadays with this kind of passive have the cooldown scale with level, so let's say from 1/6/11/16 it goes from 12/11/10/9 seconds. This encourages him to go out and auto more often if you're able to avoid his damage in sustained fights.

another idea is to give his passive a damage aspect alongside mana regeneration, something like 10-180 bonus magic damage (scaling poorly with either mana or ap) when attacking enemy champions (would still restore mana on minions, but no damage). This will encourage a xerath to more actively look to auto opponents instead of minions, leading to more counterplay.

Tell me your thoughts!