User blog comment:Ozuar/Swain's Passive/@comment-5605969-20130407100440

That would still be a bit bad. Suppose a tank has 4000 hp. If he dies, Swain gets 20 mana back. Yay for swain.

I'd suggest 2 different things. 1 - When out of combat for 7 seconds, Swain gets mana regen equal to a percentage of his max hp. Using mana will stop  the effect. (1%, / 1,5% / 2%) Or more if needed.

2- Whenever Swain kills a unit, he doubles his mana regen for 2 / 3 / 4 / 5 secs. Power of effect doubles when killing a champ, and is increased by 1.5 when assisting. Duration remains the same.