Magic Resistance. The derro has advantage on saving throws against spells and other magical effects.
Sunlight Sensitivity. While in sunlight, the derro has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
Hooked Spear. Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit:3 (1d6) piercing damage. If the target is Medium or smaller, the derro can choose to deal no damage and knock it prone.
Light Crossbow. Ranged Weapon Attack: +4 to hit, range 80/320 ft., one target. Hit:6 (1d8 + 2) piercing damage.
Mind flayers must be stopped. They have visited horrors on countless worlds, and entire groups of people have been mutated by illithid experiments. Such are the derro.