Cold Aura. While the xixecal is alive, the xixecal generates an aura of bitter cold that fills the area within 60 feet of it. Any creature that starts its turn within 60 feet of the xixecal takes 18 (4d8) cold damage.

Colossal. The xixecal is one size category bigger then Gargantuan.

Immutable Form. The xixecal is immune to any spell or effect that would alter its form.

Ice Walk. The xixecal can move across and climb icy surfaces without needing to make an ability check. Additionally, difficult terrain composed of ice or snow does not cost it extra movement.

Innate Spellcasting. The xixecal's innate spellcasting ability is Charisma (spell save DC 23, +15 to hit with spell attacks). The xixecal can cast the following spells, requiring no material components.

At will: Cone of Cold, Control Weather, Detect Magic, Dispel Magic, Elemental Bane (cold only), Freezing Sphere, Hold Monster, Ice Knife (as a 5th–level spell), Nondetection, Sleet Storm, Slow, Wall of Ice

3/day each: Power Word Stun, Time Stop

Legendary Resistance (5/Day). If the xixecal fails a saving throw, it can choose to succeed instead.

Living Storm. The xixecal is always at the center of a blizzard 10 miles in diameter. Heavy precipitation in the form of snow or hail falls there, causing the area to be lightly obscured. Strong winds swirl in the area covered by the storm. These winds extinguish open flames, disperse fog, and impose disadvantage on Wisdom (Perception) checks and ranged weapon attack rolls.

Magic Resistance. The xixecal has advantage on saving throws against spells and other magical effects.

Magic Weapons. The xixecal's weapon attacks are magical.

Regeneration. No form of attack can suppress the titan’s regeneration, it regenerates even if disintegrated or slain by a death effect. It can be banished or otherwise transported as a means to save a region, but the method to truly kill a titan has yet to be discovered. The titan regains 50 hit points at the start of each of its turns.

Siege Monster. The xixecal deals double damage to objects and structures.

Tough Immunity. The titan is immune to all diseases, and any effect that would reduce its maximum hit points.

Multiattack. The xixecal makes two claw attacks.

Claw. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 37 (5d10 + 10) bludgeoning damage, plus 27 (6d8) cold damage. On a hit, the target must succeed on a DC 23 Constitution saving throw. On a failed save, the target gains one level of exhaustion.

Cold Breath (Recharge 5–6). The xixecal exhales an icy blast in a 300–foot cone. Each creature in that area must succeed on a DC 27 Constitution saving throw. On a failed save, a creature takes 81 (18d8) cold damage, and has their movement speed halved until the start of the xixecal’s next turn. On a successful save, a creature takes half damage and does not suffer from any reduction in speed.

Glacier Swarm (1/Day). Freezing boulders of ice plummet to the ground at four different points the xixecal can see within 1 mile. Each creature in a 40–foot–radius sphere centered on each point the xixecal chooses must make a DC 23 Dexterity saving throw. On a failed save, a creature takes 67 (15d8) cold damage and 67 (15d8) bludgeoning damage. On a successful save, a creature takes half damage. A creature in the area of more than one freezing burst is affected only once.

Summon White Dragon (1/Day). The xixecal summons 1d4 + 1 Adult White Dragon. A summoned Adult White Dragon appears in the Living Storm and flies to an unoccupied space within 120 feet of the xixecal, acts as an ally of the xixecal, and rolls its own initiative. A summoned Adult White Dragon cannot use Legendary Actions or Lair Actions. It remains until it or the xixecal dies, or until the xixecal dismisses it as an action.

The xixecal can take 5 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 xixecal regains spent legendary actions at the start of its turn.

Cast Spell. The xixecal casts one of its “At–Will” spells, from its innate spellcasting.

Stomp (Cost 2 Actions). The xixecal stomps one of its large feet on the grow. Each creature in a 15–foot cube originating from xixecal must make a DC 27 Dexterity saving throw. On a failed save, a creature takes 43 (6d10 + 10) bludgeoning damage plus 27 (6d8) cold damage and is knocked prone. On a successful save, a creature takes half damage and is not knocked prone.

Absolute Zero (Costs 3 Actions). The xixecal completely absorbs all heat from the immediate vicinity, causing the temperature to plunge as low as possible (about –274 degrees Celsius or –461 degrees Fahrenheit). All creatures within 120 feet of the xixecal that are not immune to cold damage must succeed on a DC 27 Constitution saving throw. On a failed save, a creature takes 18 (4d8) cold damage and falls under the effects of the Slow spell for one minute, the xixecal does not have to maintain concentration on this slow effect. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. Creatures resistant but not immune to cold damage make this saving throw with advantage.