Tiaral

I was thinking about the healing ability; it shouldn't need to target anything, but if it's not an AoE, then Destruction becomes a completely useless perk – it only works for Domination.

That being said, AoE Domination looks pretty good. (despite the small range) Especially if it also increases the range of Destruction and single-target debuffs.

Then I'll have to take Freedom, and with it, Education and some kind of cheap unit for 50 gold, which means I'll have to rework the build.
I don't know what to do; it's too complicated.

Actually, you can leave everything as is. (or I can explain the different options in more detail later) Either way, you'll have enough mana at the beginning to summon one monster and cast one Subjugate/Arrow spell. And then, as the game progresses, you can increase your stats and upgrade your body.