You magically bind a contract written in blood. Each entity to be involved with and bound to the contract provides a vial of blood, and ritually mixed with ink. Each and every term, condition and item in the contract must be precisely written. If a term, item or condition can be interpreted in multiple ways, then the Blood Contract can be applied to all of the ways a they may be interpreted.

If a term, condition or item defined in the contract is broken by an entity whose blood is bound and no failure condition is defined explicitly, the entity must make a Wisdom saving throw once per day while the rule remains broken. On a failed save, that entity takes 20d6 psychic damage, or half that damage otherwise.