Crypt Phase Spider

Ethereal Jaunt. As a bonus action, the spider 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.

Cocoon Prey. As a bonus action, a crypt spider can cocoon a creature within 5 feet that is currently restrained  by webbing. A cocooned creature has disadvantage on ability checks and saving throws made to escape the web.

Web Sense. While in contact with a web, the spider knows the exact location of any other creature in contact with that web.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 11 Constitution saving throw, taking 18 (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.

Web (Recharge 5-6). Ranged Weapon Attack: +5 to hit, range 30/60 ft., one creature. Hit: The creature is restrained by webbing. As an action, the restrained creature can make a DC 13 Strength check, escaping from the webbing on a success. The effect also ends if the webbing is destroyed. The webbing has AC 10, 5 hp, vulnerability to fire damage, and immunity to bludgeoning, poison, and psychic damage.

Create Zombie. The crypt spider creates a zombie from a humanoid creature it has killed with its poison. This works like the animate dead spell, except the zombie stays under the crypt spider’s control for 1d4 days. At the end of this duration or when the zombie is destroyed, the corpse bursts open, releasing hundreds of crypt spider young (use swarm of spiders statistics). The crypt spider can have no more than four zombies under its control at one time.