Shifting Power. As the prism spider shifts color, its immunities and attacks change. Roll a d6 at the start of the spider’s turn and consult the table below. Use the result in place of one of the spider’s attacks.

1. Green/Acid Spit Acid. The spider spits a 30-foot line of acid that is 5 feet wide. Each creature in the line must make a DC 16 Dexterity saving throw, taking 31 (9d6) acid damage on a failed save, or half as much damage on a successful one.

2. Orange/Fire Inferno Shield. The spider is wreathed in intense, thick flames, shedding bright light in a 20-foot radius and dim light for an additional 20 feet. Whenever a creature within 5 feet of the spider hits it with a melee attack before the end of the prism spider’s next turn, the shield erupts, dealing 27 (6d8) fire damage to the creature.

3. Grey/Disease Fetid Bite. When the prism spider makes a bite attack, the target must succeed on a DC 17 Constitution saving throw against disease or become poisoned until the disease is cured. Every 24 hours that elapse, the target must repeat the saving throw, reducing its hit point maximum by 16 (3d10) on a failure. The disease is cured on a success. The target dies if the disease reduces its hit point maximum to 0. This reduction to the target’s hit point maximum lasts until the disease is cured.

4. Blue/Lightning Shocking Aura. Until the end of the spider’s next turn, creatures who enter or begin their turns within 15 feet of the prism spider must make a DC 16 Dexterity saving throw, taking 27 (6d8) lightning damage on a failed saving throw, or half as much damage on a successful one. Creatures wearing metal armor have disadvantage on this saving throw.

5. White/Cold Hoarfrost. Until the beginning of the spider’s next turn, creatures who enter or begin their turns within 15 feet of the prism spider must make a DC 16 Constitution saving throw. On a failed saving throw, the target takes 28 (8d6) cold damage. A creature who takes cold damage from this effect has their movement speed halved, cannot take reactions, and can only take one action or one bonus action on their turn. They can only make one melee or ranged attack on their turn, regardless of other class features or magic items.

6. Purple/– Heal. The spider magically heals itself for 36 (8d8) damage, and it has advantage on saving throws against spells and other magical effects until the end of its next turn.

Spider Climb. The prism 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.

Actions

Multiattack. The spider uses one of its shifting power abilities and makes a bite attack.

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 13 (2d8 + 4) piercing damage.

Web (Recharge 5–6). Ranged Weapon Attack: +7 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 14 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 10; hp 10; the same resistances that the prism spider is benefiting from at that time; immunity to bludgeoning, poison, and psychic damage).

small

monstrosity

cr9

tome-of-horrors

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