Multiattack

The derro shadowseeker makes three melee attacks.

Dagger

Melee or Ranged Weapon Attack: +8 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 7 (1d4 + 5) piercing damage.

Light Crossbow

Ranged Weapon Attack: +8 to hit, range 80/320 ft., one target. Hit: 9 (1d8 + 5) piercing damage.

Maddening Convulsions (Recharge 5-6)

The shadowseeker's body contorts and spasms in bizarre ways, confounding other creatures. Each non-derro creature within 5 feet of the shadowseeker that can see it must succeed on a DC 15 Wisdom saving throw or be affected as if by a confusion spell for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the shadowseeker's Maddening Convulsions for the next 24 hours.