Tarn Linnorm
CREATURE 20Although more powerful linnorms exist, the multi-headed tarn linnorm can wreak an awe-inspiring amount of devastation.
Immense, primeval dragons of the northern reaches of the world, linnorms hate those they deem to be lesser creatures and seek to inflict as much suffering as possible upon their unfortunate victims. While these serpentine monstrosities might not be the powerful winged dragons most imagine, they nonetheless possess incredible strength and deadly powers that often rival more notorious dragons' brutality.
A constant spell affects the monster without the monster needing to cast it, and its duration is unlimited. If a constant spell gets counteracted, the monster can reactivate it by spending the normal spellcasting actions the spell requires.
This monster can see in all directions simultaneously and therefore can't be flanked.
This monster regains the listed number of Hit Points each round at the beginning of its turn. Its Dying condition never increases beyond Dying 3 as long as its regeneration is active. However, if it takes damage of a type listed in the regeneration entry, its regeneration deactivates until the end of its next turn. Deactivate the regeneration before applying any damage of a listed type, since that damage might kill the monster by bringing it to Dying 4.
When a creature slays the tarn linnorm, it must succeed at a DC 46 Will save or it can no longer recover Hit Points via any means, such as healing spells, the Medicine skill, or natural healing from rest. This has an unlimited duration.
3d6+18 bludgeoning, DC 44 basic Fortitude
The monster deals the listed amount of damage to any number of creatures Grabbed or Restrained by it. Each of those creatures can attempt a basic Fortitude save with the listed DC.
The tarn linnorm can expel either a 120-foot line or a 60-foot cone of acid, dealing 20d6 acid damage to creatures within the area (DC 44 basic Reflex save).
The linnorm can't use Corrosive Breath or Double Breath again for 1d4 rounds.
The acid creates toxic fumes. At the beginning of the linnorm's next turn, those who failed the breath weapon's Reflex save must succeed at a DC 42 Fortitude or gain Sickened 4 from the poisonous fumes.
The tarn linnorm uses Corrosive Breath twice. A creature attempts only one save and can take damage only once.
The linnorm can't use Corrosive Breath or Double Breath again for 2d4 rounds.
The monster can instead use Improved Grab as an action and choose one creature it's grabbing or restraining with an appendage that has Improved Grab to automatically extend that condition to the end of the monster's next turn.