Acrid Curse. The Archrid is a twisted abomination made by failed transmutation magic. It is immune to shape change effects such as the polymorph spell.

Spider Climb. The 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 spider knows the exact location of any other creature in contact with the same web.

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

Multiattack. The Amalgamation makes two attacks: one with its bite and one with its Spine.

Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one creature. Hit: 17 (2d10 + 5) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 13 (4d6) poison damage on a failed save, or half as much damage on a successful one.

Wretched Bile. Ranged Weapon Attack: +8 to hit, Range 30/120, one creature. Hit: (2d8 +2) Acid damage.

Web (Recharge 5–6). Ranged Weapon Attack: +8 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 12 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).