beam of devastation

when  you use this spell roll a 1d20 to see if it will hit if it does roll a 10d20 and then after you have done damage to the creature before your turn ends you can roll a 1d20 again and if you get a natural 20 you can hit the target you had hit with the spell previously roll another 10d20 and do that damage to the creature as well after you used this spell you have to skip your next 3 turns in combat