Latent Wild Magic

You never knew it, but you have always had wild magic within you. When you die, cast any 1st-level spell and then roll three times on the wild magic surge table in the player's handbook. Also, all creatures within 30 feet of you are struck with a blast of magic that deals force damage equal to half your level. For one day, all creatures affected must make a DC 10 charisma saving throw whenever they cast a spell. On a successful save, nothing happens. On a failed save, that creature rolls on the wild magic surges table.