Bloodshield

You sacrifice your vitality to create a shield for yourself or an ally.

You immediately take Necrotic damage equal to 2d4 + your Charisma modifier; this damage cannot be reduced or prevented by resistance or immunity to Necrotic damage. The triggering target immediately gains temporary hit points equal to twice the damage you take, absorbing as much of the triggering damage as possible. If there is damage remaining, the spell ends and the ally takes all remaining damage as normal.

If used on an ally, any remaining temporary hit points disappear at the end of your next turn; if used on yourself, any remaining temporary hit points remain until you finish your next Long Rest.

Using a Higher-Level Spell Slot. The damage increases by 2d4 for each spell slot level above 1.