Eldritch empowerment

Whenever you roll damage for a spell or eldritch invocation, you can choose to spend one of your Hit Dice. If you do so, add the result of the Hit Dice roll to the damage dealt by the spell or invocation.You can use this ability once per turn.

Additionally, when you take the Attack action on your turn, you can choose to make an Eldritch Blast attack as a bonus action.