a d30 can be rolled 4 times (nothing happens counts as half a roll) 1-5 you take 2d4 damage 5-10 1d4 damage 10-15 nothing happens 15-20 nothing happens 20-25 reroll the next roll that is under 10 on a d20 you have to keep the reroll 25-29 you can use this as a ring it is sentiant and helps you get advantage on intelligence rolls 30 you get a wish spell