Grounded

You are in tune with the earth, specializing in using the ground and gravity to your advantage. While standing on the ground, you have resistance to lightning damage (If you already have resistance, this becomes immunity). When you deal damage to a grounded creature, you may reroll any number of the damage die, taking the new result. You may add your proficiency bonus to damage rolls against prone creatures. If you cast the erupting earth spell on a grounded and prone creature, double the amount of damage it deals to that creature.