PHB, p. 271
SRD
Ray of Enfeeblement
2-level Necromancy
Casting Time: 1 action
Range/Area: 12 sq.
Components: V, S
Duration: Concentration, 1 minute
Attack/Save: CON Save
A black beam of enervating energy springs from your finger toward a creature within range. Make a ranged spell attack against the target. On a hit, the target deals only half damage with weapon attacks that use Strength until the spell ends.At the end of each of the target's turns, it can make a Constitution saving throw against the spell. On a success, the spell ends.
Available for: Warlock, Wizard