Doom blade

You momentarily summon a blade made of negative energy to strike at a foe. Choose a creature you can see within range. Make a ranged spell attack against the target. On a hit, the target takes 6d8 necrotic damage, The target must succeed on a Constitution saving throw or its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0..

This spell does not effect constructs and undead.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 2d8 for each slot level above 3rd.