This effect has a cut-off point of ”30”. When activated, you roll dice until your running total equals or exceeds 30. Each roll is: Die roll + your chosen ability modifier .You must keep rolling until the cut-off is reached, no matter how many dice it takes.
then depending on what spell was used you gain:
For every die you rolled, you suffer Damage
For every die you rolled, you suffer a Dice roll x amount used to get to the cut-off point as damage
a amount of dice roll indicates how sever a de-duff is you get