You attempt to interrupt a creature in the process of casting a spell. Regardless of the Spell level of the spell you are attempting to interrupt, you must roll a d20 plut your Spell Casting Modifier. The DC equals 10 + the spell's level. On a success, the creature's spell fails, has no effect and you gain temporary hit points equal to 3 plus the spell that was interrupted

At Higher Levels When you casting this spell using a spell slot of 4th level or higher, add one addition temporary hit point for each spell level of 4th or higher