Multiattack

The derro makes two Scimitar or Heavy Crossbow attacks.

Scimitar

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) slashing damage plus 9 (2d8) necrotic damage.

Heavy Crossbow

Ranged Weapon Attack: +7 to hit, range 100/400 ft., one target. Hit: 9 (1d10 + 4) piercing damage plus 9 (2d8) necrotic damage.

Infectious Insanity (Recharge 5-6)

The shadow antipaladin magically assaults the minds of up to three creatures it can see within 30 feet of it. Each target must make a DC 13 Wisdom saving throw. On a failure, a creature takes 21 (6d6) psychic damage and is incapacitated for 1 minute as its mind fills with thoughts of eldritch terrors and otherworldly entities. On a success, a creature takes half the damage and isn't incapacitated. An incapacitated creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.