Zilean Passive Discussion

Hello everyone! I love playing Zilean in the support role and occasionally mid lane. Ever since Riot updated him they have slowly changed aspects to put him in a good spot in terms of his power and usability. The only sore spot (for me personally) is his passive.

Its true that there are some times when you can use his passive to great effect to give your teammate a power spike such as hitting level 6 in lane before your opponent; however more often than not I feel that it is underwhelming. Most of the time when you use his passive you are simply topping off a teammates xp bar, and they were going to level after another minion or two anyway. Sometimes, if you save up your xp, you can completely level someone from 0 xp to the next level, but in my experience that happens once, MAYBE twice per game.

I just got done playing a game as support Zilean and I had an idea about some way to give Zilean a more exciting effect to his passive that rewards him for focusing his xp boosting powers on one ally over the course of the game.

What if, once per game when both Zilean and his selected teammate are level 18, he could grant them knowledge of a future (to keep the concept lore friendly) in which his teammate is even more powerful? What I'm thinking is one of two things. Either he grants his teammate one extra level up, so there would be 1 level 19 player on his team, OR he would grant 1 player the ability to rank up their ultimate to level 4.

A level 4 ultimate would level up the same as the previous 3 levels in the sense that it would increase its power by the same amount. Aside from some fringe cases that I cannot think of right now, I don't feel like this would break many (if any) champions. Please feel free to correct me in the comments.

What do you all think? I feel that this would be rewarding for Zilean because it incentivizes attempting to boost a player to 18 as quickly as possible while also giving him a neat passive at level 18 whereas at the moment he has nothing.

(I apologize if there are any weird spaces between words/letters in this post, keyboard is on the fritz and is double/triple/quadruple hitting some keys.)