Infuse Minion
5e, 3/4 cast, -1 upkeep, 10 sec recharge
Attribute: Spawning Power
Target minion gains health regeneration equal to its natural degeneration, and deals 1..17 more damage with its attacks.
And because it has an upkeep, you can probably only use it on one or two minions, so maybe keep a Fleshy up. I'd appreciate some feedback, and any ideas related to this.

* Of course, if you've infused a minion with a soul, it becomes much more intelligent, I think it should get slightly improved AI - it can detach from a target, it will only attack what you're attacking.