Innate Spellcasting. The absoloth’s innate spellcasting ability is Charisma. It can cast the following spells, requiring no material components:

At will: darkness, magic missile

Magic Resistance. The absoloth has advantage on saving throws against spells and other magical effects.

Magic Weapons. The absoloth’s weapon attacks are magical.

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (2d4 + 3) slashing damage. The target must make a DC 14 Constitution saving throw, taking 10 (3d6) poison damage on a failed save, or half as much damage on a successful one.

Teleport. The absoloth magically teleports, along with any equipment it is wearing or carrying, up to 60 feet to an unoccupied space it can see.

Soul Splice. When a creature with the spellcasting or pact magic feature dies within 60 feet of the absoloth, the absoloth can use an action to splice that creature’s soul to itself. The soul remains spliced for 100 years or until lost by the absoloth, during which it cannot be returned to life. While the soul is spliced to the absoloth, the absoloth gains all cantrips and spells known or prepared (whichever is appropriate) by the target and the target’s maximum number of spell slots. It can cast these spells using the soul’s spell save DC, spell attack bonus, and spellcasting ability modifier. It can have multiple creatures spliced to it at once but can only use each creature’s spell slots on that creature’s spells. When the absoloth spends a spell slot gained from this feature, it cannot regain the spent spell slot. Whenever the absoloth takes damage while one or more souls are spliced to it, it must succeed on a DC 10 Constitution saving throw or lose one randomly determined soul.