Your primal magic forms invisible thorns that lurk just below the surface of the ground. When a foe steps on their location, the)' erupt to rend and tear flesh.
The target becomes a zone that lasts until the end of the encounter or until an enemy enters it. Without a Perception check , your enemies notice neither the zone nor your use of this power. When an enemy enters the zone, the enemy takes 5 + your Wisdom modifier damage, and it is immobilized until the end of your next turn.