Records say that some Ancients would talk to their pet plants, the plants then would react to the sound of their master's voice. Somehow you are now able to do the same, except with trees which can be commanded to bind enemies with their twisted roots.
Area effect. Disables enemy movement for 1 turn. 2 kills to recharge.
Note: The in-game description is inaccurate. Tree Hugger disables enemy movement for 2 turns.