rare n gargantuan beast fire 

Perception +25; darkvision, tremorsense (imprecise) 100 feet

Skills Athletics +38

Str +10 Dex -1 Con +9 Int -3 Wis -1 Cha -1

AC  40; Fort +36, Ref +25, Will +27

HP 410; Immunities fire; Weaknesses cold 15

Fire Healing As long as a crimson worm is in contact with a fire or body of magma at least as large as itself, it gains fast healing 20. When struck by a magical fire effect from anything other than itself, a crimson worm regains Hit Points equal to half the fire damage the effect would otherwise deal.

Inexorable The crimson worm recovers from the paralyzed, slowed, and stunned conditions at the end of its turn. It's also immune to penalties to its Speeds and the immobilized condition, and it ignores difficult terrain and greater difficult terrain.

Shake It Off [R] Frequency once per day; Trigger The crimson worm would be affected by a condition or adverse effect (such as baleful polymorph). Effect The crimson worm negates the triggering condition or effect. Effects from artifacts, deities, or a similarly powerful source can't be avoided in this way.

Speed 40 feet, burrow 40 feet, swim 20 feet

Melee [>] jaws +36 (deadly 3d10, fire, reach 20 feet), Damage 3d10+18 piercing plus 2d6 fire and Improved Grab

Melee [>] stinger +36 (agile, fire, poison, reach 20 feet), Damage 2d12+18 piercing plus 2d6 fire and crimson worm venom

Melee [>] body +34 (fire, reach 15 feet), Damage 2d10+16 bludgeoning plus 2d6 fire

Breath Weapon [>>] (evocation, fire, primal) The crimson worm breathes a blast of flame in a 60-foot cone that deals 18d6 fire damage to all creatures in the area (DC 41 basic Reflex save). It can't use Breath Weapon again for 1d4 rounds.

Crimson Worm Venom (poison) Saving Throw DC 41 Fortitude; Maximum Duration 6 rounds; Stage 1 1d6 poison damage and drained 1 , (1 round); Stage 2 2d6 poison damage and drained 1 (1 round); Stage 3 2d6 poison damage and drained 2. (1 round)

Fast Swallow [R] Trigger The worm Grabs a creature. Effect The worm uses Swallow Whole.

Rock Vrorouth A crimson worm can burrow through solid stone at a Speed of 20 feet. It can leave a tunnel if it desires, and it usually does.

Swallow Whole [>] Huge, 3d10+10 bludgeoning plus 2d6 fire, Rupture 36.

Thrash [>>] The worm makes a Strike once against each creature in its reach. It can Strike up to once with its jaws, up to once with its stinger, and any number of times with its body. Each attack counts toward the worm's multiple attack penalty, but the multiple attack penalty doesn't increase until after it makes all the attacks.

Bestiary, page 59.