By 6th level, you've learned the history of the Primordials and their banishment, making you vengeful. After successfully landing an attack with one of your Warlock cantrips, you can expend a spell slot to make it more powerful. A cantrip augmented this way gains a bonus to its damage equal to 2d6 per level of spell slot expended. The damage type of this extra damage is the same as the initial cantrip damage.