By the way, when I attack with Agrael, my demons steal all 70 mana units from Talanar. If druids are still present, they don't transfer mana to him, but he still constantly casts evasion. How can this be explained?!
You just need to check if Talanar has, for example, an "Amulet of Mana Absorption" or, perhaps, a wand or scroll.
