Start on "Hero".

How did you manage to kill 2 stacks at once if they usually stand more than 2 tiles apart? Or were they conveniently positioned? But yes, taking out the red ones early in the game is great, they are quite overpowered.

It seems that when they split into 4 stacks, 2 of the stacks are close enough to each other.

I generally don't like playing as mages, just like I don't like playing as Inferno. Perhaps they are strong in the late game due to their mini-artifacts, but Haven easily defeats them, even if the mage has a high knowledge stat.