Drider

Armor Class 19 (natural armor)
Hit Points 123 (13d10 + 52)
Speed 30 ft., climb 30 ft.

Skills Perception +5, Stealth +9
Senses darkvision 120 ft., passive Perception 15
Languages Elvish, Undercommon
Challenge 6 (2,300 XP)

Fey Ancestry. The drider has advantage on saving throws against being charmed, and magic can't put the drider to sleep.
Innate Spellcasting. The drider's innate spellcasting ability is Wisdom (spell save DC 13). The drider can innately cast the following spells, requiring no material components:
At will: dancing lights
1/day each: darkness, faerie fire
Spider Climb. The drider can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check. Sunlight Sensitivity. While in sunlight, the drider has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
Web Walker. The drider ignores movement restrictions caused by webbing.

Actions

Multiattack. The drider makes three attacks, either with its longsword or its longbow. It can replace one of those attacks with a bite attack.
Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 2 (1d4) piercing damage plus 9 (2d8) poison damage.
Longsword. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) slashing damage, or 8 (1d10 + 3) slashing damage if used with two hands.
Longbow. Ranged Weapon Attack: +6 to hit, range 150/600 ft., one target. Hit: 7 (1d8 + 3) piercing damage plus 4 (1d8) poison damage.