Energy Drain

You imbue your hand with a cackling surge of negative energy. You make a melee spell attack against a creature, on a successful hit the target must make a Constitution saving throw or lose 2d4 levels for the duration. A creature that has lost class levels from this effect temporarily loses access to all class features and abilities gained from those levels. If the target loses as many levels as it has Hit Dice, it dies instantly. If a creature does not have levels, it simply loses Hit Dice instead.

If the spell heal is cast on the target during the spell's duration, the target regains all lost levels and the spell ends.

An Undead creature targeted by this spell instead gains 10d4 temporary hit points for the duration.

This spell has no effect on Constructs.