The way way treants currentky are is extremely gimmicky. One die and you INSTANTLY get another free. I used this to destroy a dragon, defeat an army around my capital, and get infite friendliness with a city state all with no cost to myself. If possible, they should respawn the turn AFTER you lose them and not be giftable. They are also too weak to use beyond the very early game. They should get stronger as you unlock more magic so they don't fall off so hard.