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.

Actions

Quarterstaff.

Melee Weapon Attack: +1 to hit, reach 5 ft., one target. Hit: 2 (1d6 - 1) bludgeoning damage.

Chromatic Beam.

The derro launches a brilliant beam of magical energy in a 5-foot-wide line that is 60 feet long. Each creature in the line must make a DC 12 Dexterity saving throw, taking 21 (6d6) radiant damage on a failed save, or half as much damage on a successful one.

Spellcasting.

The derro casts one of the following spells, using Charisma as the spellcasting ability (spell save DC 12):

At will: mage hand, message, prestidigitation
1/day each: invisibility, sleep, spider climb

Environment: Underdark

Derro Savant