Dark Pact

You touch a creature, and that creature must succeed on a Wisdom saving throw or become affect by this pact for the duration of the spell. A creature can choose to fail this spell. When you cast this spell, choose the nature of the pact from the following options:

Blood Curse:  Target takes half of all damage it deals to caster, this damage cannot be reduced in any way. Spells that only target the caster grant the caster advantage on saving throws.

Blood Boon: As an action, Target and Caster are able to spend hit dice to roll and transfer hit points as 1 Hit Die + Con modifier of the target. The party sending the hit points takes half the damage of the healing dealt, this damage cannot be reduced in any way.

At Higher Levels. If you cast this spell using a spell slot of 3th level or higher, the duration is concentration, up to 10 minutes. If you use a spell slot of 4th level or higher, the duration is 8 hours. If you use a spell slot of 6th level or higher, the duration is 24 hours.