Curse of Wild Magic

You see a creature within 120ft and place a curse mark on them taking up 10% of they’re body, this Mark is solid black and takes the shape of a blob wherever it’s placed, if the cursed person is a spell caster they have a chance for they’re magic to go wild, this chance is a percentile roll based on how much the curse covers, the curse percentage grows every time wild magic goes off by 1 * spell level, if it is a cantrip it cannot go wild.