Special Equipment. Droki wears boots of speed.
Insanity. Droki has advantage on saving throws against being charmed or frightened.
Sneak Attack (1/Turn). Droki deals an extra 7 (2d6) damage when he hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of Droki that isn't incapacitated and Droki doesn't have disadvantage on the attack roll.
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.
Innate Spellcasting. Droki's innate spellcasting ability is Charisma (spell save DC 13). He can innately cast the following spells, requiring no material components:
At will: minor illusion
Multiattack. Droki makes two attacks with his shortsword
Shortsword. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit:6 (1d6 + 3) piercing damage. The sword is coated with serpent venom that wears off after the first hit. A target subjected to the venom must make a DC 11 Constitution saving throw, taking 10 (3d6) poison damage on a failed save, or half as much damage on a successful one.
Parry. Droki adds 3 to his AC against one melee attack that would hit him. To do so, Droki must see the attacker and be wielding a melee weapon.
Droki hates everyone in general and surfacers in particular. He gnashes his teeth if he has to address the characters, taking every opportunity to be insulting and misleading. If the characters look through his satchel while he's still conscious, he throws an epic tantrum and becomes intractable until knocked unconscious.