When you cast freeze blood as a successful melee spell attack against a living creature with a circulatory system, the creature’s blood freezes. For the spell’s duration, the affected creature’s speed is halved and it takes 2d6 cold damage at the start of each of its turns. If the creature takes bludgeoning damage from a critical hit, the attack’s damage dice are rolled three times instead of twice. At the end of each of its turns, the creature can make a Constitution saving throw, ending the effect on a success.