Wizard – “Hope of Zephyr” [Campaign 6, Mission 5]

I'm not very good at this game; I play it very rarely, just for fun, but I can't seem to beat the last mission no matter what I try. None of the four have "Exile." I tried to level them up in the previous mission, but it didn't work... In the final battle, the Mage on the "elephant" gets taken down, and that's it... I shared Archangels from Godric with him, but it didn't help...
I don't know what to do; it's so frustrating...