I really enjoyed this game. I like tower-defense-style games and this had that vibe. I will say, in the first play I was a bit lost, but understood the rules by the 2nd time and won the 2nd go.
The mechanic of summoning allies and being able to play them at will was a cool concept. I think to add some difficulty, it would be cool if the enemies did some damage to either the mage or your summoned warriors. As is, the game became a bit easy towards the end when I amassed a decent-sized army with no risk of destruction.
Overall, fun game!