Burning The Lifeblood

This brutal and disabling spell attacks the very blood coursing through the target's veins. The caster ignites cells within the blood stream effectively burning them with their own water. The target takes 4d6 fire damage every round and must make a constitution save or they can only take a partial action during their next turn. The target gets a constitution save before damage begins to negate the spell before it begins and a successful save during a round ends the spell.