Ethereal Jaunt. As a bonus action, the phae drider can magically shift from the Material Plane to the Ethereal Plane, or vice versa.

Spider Climb. The spider can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Web Walker. The spider ignores movement restrictions caused by webbing.

Innate Spellcasting. The phase drider's spellcasting ability is wisdom (spell save DC 16, +7 to hit with spell attacks).  It can innately cast the following spells, requiring no material components:

At will: Dancing Lights

3/day:darkness, faerie fire

Spellcasting. The phase drider is a 10th-level spellcaster. Its spellcasting ability is wisdom (spell save DC 16, +7 to hit with spell attacks). The phase drider has the following cleric prepared

cantrip (at will): poison spray, thaumaturgy

1st level (4 slots): charm person, detect magic, sanctuary

2nd level (3 slots): hold person,silence

3rd level (3 slots) counterspell, dispel magic

4th level (3 slots): freedom of movement, Greater invisibility

5th level (2 slots): synaptic static, dominate person

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 16 Constitution saving throw, taking 4d8 poison damage on a failed save, or half as much damage on a successful one. If the poison damage reduces the target to 0 hit points, the target is stable but poisoned for 1 hour, even after regaining hit points, and is paralyzed while poisoned in this way.

Multi-Attack. The Phase Drider makes 2 swings with her Onyx LongSword or 2 shots with her onyx longbow. it can replace one of those attacks with a bite or a web.

Onyx Long Sword Swing. Melee weapon attack: +9 to hit, reach 5 ft. Damage 1d10+5 or(2d10 +5 if two handed) magical damage + 1d6 Poison damage.

Onyx Longbow. Ranged weapon attack: +9 to hit Range(150/600)ft. damage 1d10+5 magical damage and 1d6 poison damage.

Web. Ranged Weapon Attack: +10 to hit, range 30/60 ft., one creature. Hit: The target is Restrained by webbing. As an action, the Restrained target can make a DC 16 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 10; hp 5; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).