Insanity. The derro has advantage on saving throws against being charmed or frightened.
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 Shortspear. Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit: 1 ( 1d4-1 ) piercing damage. If the target is a creature, the derro can choose to deal no damage and try to trip the target instead, in which case the target must succeed on a DC 9 Strength saving throw or fall prone.
Light Repeating Crossbow. Ranged Weapon Attack: +4 to hit, range 40/160 ft., one target. Hit: 6 ( 1d8+2 ) piercing damage.