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

Web Sense. While in contact with a web, the Abyssal Spider knows the exact location of any other creature in contact with the same web.

Web Walker. The Abyssal Spider ignores movement restrictions caused by webbing.

Temporary Energy Consumption. The Abyssal Spider can stack temporary life points gained by their attacks. 

Abyssal Darkness (Recharge 10). The Abyssal Spider Creates a cloud of darkness in a 15 foot radius with itself in the center. This darkness lasts for 3 turns, and anyone who is in it takes 12 (2d6 + 6) force damage. Abyssal Spider can sacrifice 10 temporary hitpoints to have the darkness deal an additional 2d6 damage.

Multiattack. Abyssal Spider makes 1 Abyssal Greed and 2 Bite attacks.

Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one creature. Hit: 32 (4d12 + 8) piercing damage, and the target must make a DC 16 Constitution saving throw, or else 10 (1d12+4) temporary hitpoints will be given to Abyssal Spider. Half as much on a successful save. 

Abyssal Greed. Melee Weapon Attack: +8 to hit, reach 10 ft., one creature. The Creature targeted is grappled and must make a DC 14 Constitution saving throw every turn while grappled, or else take 12 (2d6 + 6) force damage. Abyssal Spider can sacrifice 10 temporary hitpoints to have the darkness deal an additional 2d6 damage.

Abyssal Lullaby. Range Weapon Attack: All creatures in a 50 foot radius of Abyssal Spider must make a DC 15 Wisdom saving throw, or they will be put to sleep. Deafened creatures have immunity, and creatures who understand Abyssal have advantage. This lasts until the Abyssal Spider's next turn, until the Creature is damaged, or if the creature succeeds the DC saving throw on it's next turn. Abyssal Spider can sacrifice 10 temporary hitpoints to extend this effect for an additional turn.