You try to interrupt a creature in the process of casting a spell. You make a skill check using your spell-casting ability. DC equals 10 + Spell Level. On success, the spell fails and has no effect, additionally you regain hit points equal to 3d6 + spell level.

If the spell's level is less than the level of space spent to cast that spell, you make the roll to advantage.

At Higher Levels: When you cast this spell at higher levels, healing increases by 1d6 for each level above 4th.