Toby's terrible tail

summons a giant dog tail from the ground to attack enemies. user must make an accuracy check, if you roll a 1-10 you get hit for 4d8 bludgeoning damage, if you roll a 11-20 al enemies in a 15 foot radius take 4d8 bludgeoning damage. rolling a 1 does double damage to you and rolling a 20 does double damage to the enemies. this spell does double damage on constructs and warforged. every turn for 3 turns after this spell has been cast you must roll the check again to determine who the tail hits that turn.