Yochlol

If the yochlol dies outside the Abyss, its body dissolves, and it gains a new body instantly, reviving with all its Hit Points in the Abyss.

The yochlol has Advantage on saving throws against spells and other magical effects.

The yochlol can climb difficult surfaces, including along ceilings, without needing to make an ability check.

The yochlol ignores movement restrictions caused by webs.

The yochlol casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 15):

At will: Detect Thoughts, Gaseous Form (self only), Web

1/day: Dominate Person

The yochlol makes two Caustic Lash attacks, and it can use Spellcasting to cast Web or Dominate Person if available.

Melee or Ranged Attack Roll: +8, reach 10 ft. or range 120 ft. Hit: 25 (6d6 + 4) Acid damage.

The yochlol shape-shifts into a Medium Humanoid or a Medium spider or back into its true form. Its game statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed.

Trigger: The yochlol is hit by an attack roll. Response: The yochlol halves the attack's damage to itself (round down), and it teleports to an unoccupied space it can see within 30 feet of itself. Constitution Saving Throw: DC 15, each creature within 5 feet of the yochlol's destination space. Failure: The target has the Poisoned condition until the end of its next turn. While Poisoned, it has the Incapacitated condition.