I agree with Born to Die on this point. Overall, I envision it like this: 1. Mages could have something like a tent that restores mana to units or the hero (preferably to units first, and then to the hero). 2. For Necromancers, we could come up with something like a dark energy collector that draws energy from corpses or the pain of enemies (in which case, it would depend on the amount of hit points lost by the enemies). 3. Orcs could have a totem that, depending on the hero's level, increases rage and even accumulates it as a separate unit (from shouts, killing), and then releases it as needed. The creative process continues for the other factions, but I will definitely come up with something during the game.