A creature born in ancient times, this great has a power that can sometimes rival even the mighty Tarrasque. Its name, Wyros, means "Great Serpent" in an ancient, long-forgotten language. Where it came from is unknown, but it exists only to consume everything that comes into its path.

It spends most of its time slumbering deep underground, and awakens every 100 years to consume and feed before returning to its lair. It is said that this creature's eyes can turn all it looks it into solid blocks of stone, and its scales provide it with a limited magical immunity.

Wyros, the Great Serpent

Gargantuan monstrosity, unaligned

Armor Class 24 (natural armor)

24 (natural armor) Hit Points 585 (30d20 + 270)

585 (30d20 + 270) Speed 40 ft. burrow 60 ft.

STR DEX CON INT WIS CHA 30 (+10) 16 (+3) 28 (+9) 6 (-2) 12 (+1) 6 (-2)

Saving Throws Str +18, Con +17, Wis +9

Str +18, Con +17, Wis +9 Damage Immunities poison, bludgeoning, piercing, and slashing from nonmagical weapons

poison, bludgeoning, piercing, and slashing from nonmagical weapons Condition Immunities charmed, frightened, paralyzed, poisoned

charmed, frightened, paralyzed, poisoned Senses blindsight 60 feet, passive perception 11

blindsight 60 feet, passive perception 11 Languages —

— Challenge 28 (120,000 XP)

Legendary Resistance (3/Day). If Wyros fails a saving throw, it can choose to succeed instead.

Limited Magic Immunity. Wyros can't be affected or detected by spells of 2nd level or lower unless it wishes to be. It has advantage on saving throws against all other spells and magical effects.

Siege Monster. Wyros deals double damage to objects and structures.

Actions

Multiattack. Wyros uses it's Frightful Presence, then makes three attacks: one with its bite, one with its constrict, and one with its tail. It can use Swallow instead of the bite attack.

Bite. Melee Weapon Attack: +18 to hit, reach 15ft., one target. Hit: 36 (4d12 + 10) piercing damage plus 35 (10d6) poison damage. If the target is a creature, it is grappled (escape DC 20). Until this grapple ends, the target is restrained, and Wyros can't bite another target.

Constrict. Melee Weapon Attack: +18 to hit, reach 10 ft., one creature. Hit: 28 (4d8 + 10) bludgeoning damage. The target is grappled (escape DC 20). Until this grapple ends, the creature is restrained, and Wyros can't constrict another target

Tail. Melee Weapon Attack: +18 to hit, reach 20ft., one target Hit 37 (6d8 + 10) bludgeoning damage.

Swallow. Wyros makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite's damage and is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside of Wyros, and it takes 56 (16d6) acid damage at the start of each of Wyros's turns. If Wyros takes 35 damage or more on a single turn from a creature inside it, Wyros must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the Wyros. If Wyros dies, a swallowed creature is no longer Restrained by it and can escape from the corpse by using 30 feet of movement, exiting prone.

Frightful Presence. Each creature of Wyros's choice that is within 120 feet of it and aware of it must succeed on a DC 20 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Wyros' Frightful Presence for the next 24 hours.

Stone Gaze (Recharge 5-6). Wyros fixes its eyes on a creature within 80 feet of it. The creature must succeed on a DC 20 Constitution saving throw or become petrified in stone on a failed save. The creature can repeat the saving throw at the end of each of its turn, ending the effect on a success. If it fails the saving throw three more times, it will be permanently turned to stone, and can only be restored to normal by means of Greater Restoration or Wish

Poison Breath (Recharge 4). Wyros exhales noxious gas in a 90-foot cone. Each creature in that area must make a DC 20 Constitution saving throw, taking 91 (26d6) poison damage on a failed save, or half as much damage on a successful one.

Legendary Actions

Wyros can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. Wyros regains spent legendary actions at the start of its turn.

Burrow. Wyros burrows up to its movement speed. This movement doesn't provoke opportunity attacks.

Chomp (Costs 2 Actions). Wyros makes a bite or swallow attack.

Gaze of Stone (Costs 3 Actions). Wyros recharges its Stone Gaze, and immediately uses it.