Blood Into Mana

Upon casting this spell you can regain one spell slot up to the number of d20 damage die you are willing to take in necrotic damage plus the level of the spell slot you are restoring. The damage from this can not be reduced in any way. And the damage done cannot be restored until you take a long rest. For example to regain a 2nd level spell slot you would take 2 d20+2 necrotic damage. A 9th level spellslot would cost you 9 d20 +9 necrotic damage

If you use this to restore a pact slot as a warlock you take d20s in damage equal to the highest level spell you can cast plus the level of that spell