Dark Devotion. The cultist has advantage on saving throws against being charmed or frightened.
Fey Ancestry. The drow cultist has advantage on saving throws against being charmed, and magic can't put the drow cultist to sleep.
Sunlight Sensitivity. While in sunlight, the drow cultist has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
Innate Spellcasting. The drow cultist's innate spellcasting ability is Charisma (spell save DC 10). The drow cultist can innately cast the following spells, requiring no material components:
At will: dancing lights
1/day each: darkness, faerie fire, levitate (self only)
Scimitar. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit:4 (1d6 + 1) slashing damage.