User blog comment:Ozuar/Swain's Passive/@comment-9713132-20130407044158

I've got an idea - it's basically yours combined with Thresh's passive:

"Whenever an enemy unit dies, they leave behind a Food (name can be changed, I'm just that dead of ideas). When Swain moves within 100 units of a Food, Beatrice retrieves it, and he restores 0.5% (I'd rather 1%, with reasoning below) of their maximum health as mana".

This gives Swain an incentive to get in close to minion waves and perhaps the enemy (which is already in his playstyle) as well as slightly tone down how powerful it could be in lane, aka. you trade some mana restoration for possible damage by the enemy.