Blood Pact

Forge a magical contract with a creature you can touch, pricking yourself and the target with the needle used in the casting.

You and the target must agree to the terms of the contract, whether verbal or written, which must clearly define actions or inaction to be performed by one or both parties within or for a specified time limit not to exceed 365 days. The terms of the contract cannot compel a creature to perform an action that would directly result in its certain death or debilitating self-harm, nor can they compel inaction that would directly result in its certain death, significant harm, or permanent debilitation. The terms of the contract also cannot contradict themselves or the terms of another casting of Blood Pact (e.g. a target cannot be ordered to go home if they have also been ordered to never return home by this spell). If such terms are agreed upon, the spell immediately fails. Both parties must visibly or verbally agree for this spell to work, but the spell does not differentiate between true agreement and agreement made under duress or by coercion.

Once both parties agree on the contract's terms, they become magically bound by the contract until it is fulfilled, violated, or broken by an effect that dispels magic or removes curses. While under the effects of this spell, each creature bears a black, ring-like mark on one of its fingers (chosen while casting) or a similar appendage. If this spell ends or is dispelled, both parties immediately become aware of its ending, and both marks fade.

Should the DM determine that either party acts in a way explicitly contrary to the literal wording of the agreed-upon terms, or fails to complete its specified action within the established time limit, that creature must make a Wisdom saving throw. A creature takes 10d10 Psychic damage on a failed save, and the finger or appendage bearing the spell's mark is immediately severed from its body. On a successful save, a creature only takes half as much damage and suffers no additional effects. Pass or fail, the spell then ends.

Once the terms of the contract are fulfilled, the spell ends.

Using a Higher-Level Spell Slot. When you cast this spell using a level 6+ spell slot, the amount of damage dealt increases by 2d10 for each slot level above 5.