Mages are enemies in Solomon's Key.
Mages are particularly dangerous. They share your ability to create blocks, but not the ability to destroy them. They can, however, destroy blocks hit headbutts, just like you. In fact, they can destroy an entire block with just one headbutt. They can also jump, even higher than the player can. They aren't too bright, but they are determined. The Earth Mage is replaced by Willy in the NES version, a far smaller threat that behaves much more like a Goblin.