Titanic titan/celestial, chaotic evil
Armor Class 45 (natural armor)
Hit Points 33275 (550d100+5500)
Speed 250 ft., burrow 250 ft.
Saving Throws Strength + 20, Constitution + 20, Wisdom + 17, Charisma + 20
Skills Perception + 17
Damage Resistances All nonmagical damage
Damage Immunities Psychic, Poison
Condition Immunities charmed, frightened, grappled, paralyzed, petrified, poisoned, prone, stunned
Senses passive Perception 27
Languages celestial, abyssal, telepathy 1000000000000 km
Challenge 165 (1E25 XP)
REALLY SUPER MASSIVE. The titan is 125 km long and 25 km wide and has a head on the front of its body that is 25 km wide and 30 km long.
Heavy crusher. The worm can enter the space of any creature that is smaller than it (3000 km2 or smaller). When it does so, the creature is allowed to make a DC 48 Dexterity save. On a failed save the creature takes 200d100 bludgeon damage and is grappled until the worm moves away from it. On a successful save, the creature is allowed to make a standing jump. If it is still in the worm's space after jumping, it takes 200d100 bludgeon damage and is grappled until the titan moves.
Magic being. All damage dealt by the titan counts as being magical. It is immune to spells of 4th level or lower and has advantage on spell saving throws.
Legendary resistance (10/day). If the titan fails a saving throw it may choose to succeed instead.
Multiattack. The titan uses its frightful presence, then uses its breath weapon or bite attack.
Bite. Melee Weapon Attack: +40 to hit, targets in 25x30 km area centered at a point within 30 km of its head. Hit: 15150 (300d100+10) slashing damage damage.
Breath (recharge 4-6). The titan uses one of the following breath attacks:
Fire breath. The titan exhales a 60 km cone of fire. Any creature in the area must make a DC 48 Dexterity save or take 20d100x15 fire damage on a failed save or half as much on a successful one.
Cold breath. The titan exhales a 60 km cone of icy cold. Any creature in the area must make a DC 48 Constitution save or take 20d100x15 cold damage on a failed save or half as much on a successful one.
Poison breath. The titan exhales a 60 km cone of liquid poison. Any creature in the area must make a DC 48 Constitution save or take 18d100x15 poison damage and be poisoned for a year on a failed save or half as much damage without being poisoned on a successful one.
Magic breath. The titan exhales a 60 km cone of pure magical energy. Any creature in the area must make a DC 48 Wisdom save or take 20d100x12 force damage and lose all magical abilities (spellcasting included) on a failed save or take half as much damage and retain magic on a successful one.
Frightful presence. Any creature of the titan's choice that can see the titan must make a DC 48 Wisdom save or become frightened of the titan for 5 days. On a successful save the creature is immune to the titan's frightful presence for 3 hours. A creature that slays the titan and has been targeted by its frightful presence is immune to all effects that would frighten it.
The titan can take 10 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. The titan regains spent legendary actions at the start of its turn.
Move. The titan moves up to its speed without provoking orpotunity attacks.
Take control (6 actions). The titan targets a creature within range of its telepathy. That creature must make a DC 48 Wisdom save. On a failed save the creature obeys the titan's mental commands for 1d10 turns.