Blood Fire Strike

You take 16 damage as you cast this spell. Make a melee spell attack, on a hit the target makes a constitution saving throw if they fail they take 4d10 fire damage and 4d10 necrotic damage, the target's maximum hit points are reduced by the damage dealt this way and cannot regain hit points until the beginning of your next turn. On a success they take half as much damage and their maximum hit points are not reduced, but still cannot regain hit-points until the start of your next turn.  You may cast this spell at higher levels, you take an additional 4 points of damage and deal an additional 1d10 of fire damage and 1d10 necrotic damage for each spell level 5th and above.