you touch one creature. it takes 12d10 acid damage. on your next turn, you can use an 8th level spell slot to do 10d8 bludgeoning damage to the same creature as an action. on the turn after that, you can do 8d6 cold damage to it as an action by using a 7th level spell slot. the turn after that, you can use your action to do 6d4 fire damage to it by using a 6th level spell slot. on the turn after that, you can use your action to do 4d6 damage to yourself and kill the creature.