Composed of silvery, chitin segments as large as a human child, the insect crawls across the blighted ruins within which it nests. No doubt this silverfish would only be considered vermin to the gods themselves, for now it is a scouring predator feeding on flesh and magic alike. The behemoth has consumed so many scrolls and spell books that it crackles with an arcane force all its own; a hungering sorcery eager to consume more magical energy. Long antennae hang from its brow, stained red from many meals and often with skulls and other bones spiked by its spines.

History's Bane. So complete is the devastation that The Pariah brings, that his reality-warping abilities effects and employees even the lowest of vermin to its cause. Silverfish, usually content with nibbling on skin cells and demolishing paper, are elevated into veritable war machines. The swarms seek out holy texts, spellbooks and scroll first and foremost, crippling magical opposition to their leperous lord. This glutting bulks the insects quickly as they move onto written histories next, and then the people who read and write them. In time, a few of the silverfish swell to thirty feet in length and become true behemoths.

Silverfish Behemoth

Huge aberration, unaligned

Armor Class 16 (natural armor)

Hit Points 115 (11d12 + 44)

Speed 50ft

Str 21 Dex 13 Con 18 Int 1 Wis 12 Cha 3

Saving Throws Wis +4

Senses tremorsense 30 ft., passive Perception 11

Damage Immunities poison

Condition Immunitiescharmed, frightened

Languages -

Challenge 7 (2900 XP)

Backlash.

Any time the silverfish behemoth succeeds on a save against a spell or is missed by a ranged spell attack, roll on the Wild Magic table and apply the effects as if the silverfish behemoth cast a spell.

Magic Resistance.

The silverfish behemoth has advantage on saving throws against spells and other magical effects.

Sense Magic.

The silverfish behemoth senses magic within 120 feet of it at will. This trait otherwise works like the detect magic spell but isn't itself magical.

Actions

Multiattack.

The silverfish behemoth can make two antennae attacks as one action.

Antenna.

Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d10+5) slashing damage. In addition, any creature concentrating on a spell suffers disadvantage on maintaining concentration against the damage of this attack.

Bite.

Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 27 (4d10+5) piercing damage. In addition, any creature concentrating on a spell suffers disadvantage on maintaining concentration against the damage of this attack.

Consume Magic.

Melee Spell Attack: +8 to hit, reach 60 ft., one target. Hit: Make a Dispel Magic ability roll with a +5 against one spell the target is maintaining or has cast on them. If the spell is dispelled, the creature takes necrotic damage equal to the spell level and the silverfish behemoth regains 1d6 hit points per spell level dispelled.

Optional Rule: Mindfire

After fighting a silverfish behemoth, each character that took damage from the aberration must succeed on a DC 13 Constitution save or contract Mindfire as per the Contagion spell rules.