Aurumbrand, the Sundial Colossus

Traits

• Legendary Resistance (3/Day). If Aurumbrand fails a saving throw, it can choose to succeed instead. Each use darkens one of the twelve hour-plates orbiting its shoulders, and a darkened plate does not relight until dawn.
• Immutable Form. Aurumbrand is immune to any spell or effect that would alter its form. Its proportions were fixed by a surveyor's decree that is still legally binding in four kingdoms.
• Magic Resistance. Aurumbrand has advantage on saving throws against spells and other magical effects.
• Siege Monster. Aurumbrand deals double damage to objects and structures. It was built to correct architecture that had drifted out of alignment with the sun, and it has never been told to stop.
• Sundial Aegis. While at least one hour-plate is lit, Aurumbrand knows the exact time at any location it has ever stood, and it cannot be surprised. Any creature that ends its turn within 15 feet of Aurumbrand while three or more plates are lit takes 10 (3d6) radiant damage from focused light.

Innate Spellcasting

Their spellcasting ability is Wisdom (spell save DC 20, +12 to hit with spell attacks).

• At will. Detect Magic, Light, See Invisibility
• 1/day each. Sunbeam, Sunburst, Time Stop, Wall of Force

Actions

• Multiattack. Aurumbrand makes three attacks: two with its Gnomon Blade and one Solar Lance. It can replace one attack with a use of Hourfall if available.
• Gnomon Blade. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 36 (4d12 + 10) bludgeoning damage. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 36 (4d12 + 10) bludgeoning damage plus 13 (3d8) radiant damage. If the target is a Large or smaller creature, it must succeed on a DC 25 Strength saving throw or be knocked prone and pushed 15 feet away.
• Solar Lance. Ranged Weapon Attack: +14 to hit, range 300 ft., one target. Hit: 33 (6d10) radiant damage. Ranged Weapon Attack: +14 to hit, range 300 ft., one target. Hit: 33 (6d10) radiant damage. A creature reduced to 0 hit points by this attack is disintegrated, leaving only a scorched silhouette on whatever lay behind it.
• Hourfall (Recharge 5-6). Aurumbrand drops its shadow through an hour that has not happened yet. Each creature in the area must make a DC 24 Constitution saving throw, taking 54 (12d8) radiant damage on a failed save, or half as much damage on a successful one. On a failed save, a creature is also incapacitated for 1 round. Each creature within 60 feet must make a DC 24 Constitution saving throw, taking 54 (12d8) radiant damage on a failed save, or half as much on a successful one. A creature that fails by 5 or more also ages one year per hour-plate currently lit, and loses one action on its next turn as it re-synchronises with the present.

Bonus Actions

• Relight a Plate. Aurumbrand relights one darkened hour-plate. It regains one use of Legendary Resistance if fewer than three are currently available, and the nearest creature within 15 feet takes 10 (3d6) radiant damage as the plate catches.

Reactions

• Retrograde. Trigger: When a creature Aurumbrand can see within 60 feet hits it with an attack. Aurumbrand runs the last second backwards. The triggering attack instead misses, and the attacker must succeed on a DC 24 Wisdom saving throw or be unable to take reactions until the end of its next turn, its own recent memory briefly overwritten.

Legendary Actions

Aurumbrand, the Sundial Colossus 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. Aurumbrand regains spent legendary actions at the start of their turn.

• Advance the Shadow. Aurumbrand moves up to 30 feet without provoking opportunity attacks. Its shadow arrives first; each creature whose space the shadow crosses takes 7 (2d6) cold damage.
• Cast a Long Shadow (Costs 2 Actions). A 60-foot line of shadow extends from Aurumbrand in a direction of its choice. Each creature in the line must make a DC 24 Dexterity saving throw, taking 21 (6d6) cold damage on a failed save and having its speed halved until the end of its next turn, or half as much damage on a success.
• Noonstrike (Costs 3 Actions). Aurumbrand fixes every lit plate on one point. One creature it can see within 300 feet must make a DC 24 Constitution saving throw, taking 45 (10d8) radiant damage on a failed save, or half as much on a success. On a failure the target is also blinded until the end of its next turn, and any illusion or invisibility affecting it ends.

Lair Actions

• The Hour Turns. The great bronze plates in the floor rotate. Each creature not standing on a lit plate must succeed on a DC 22 Dexterity saving throw or be moved 20 feet toward the nearest wall and knocked prone. Each creature within 60 must make a DC 22 Dexterity saving throw.
• Cast the Gnomon. A blade of shadow sweeps across the observatory floor. Each creature in a 10-foot-wide, 60-foot line takes 18 (4d8) cold damage, or half as much with a successful DC 22 Dexterity saving throw. Aurumbrand can see through this shadow as though it were a window. Each creature within 60 must make a DC 22 Dexterity saving throw, taking 18 (4d8) cold damage on a failed save, or half as much damage on a successful one.
• Noon Held Open. Light floods the chamber and time thickens. Until the next lair action, the area within 120 feet is brightly lit, no creature can become invisible or hidden there, and any creature that tries to teleport out must first succeed on a DC 22 Charisma saving throw or lose the action. Each creature within 120 must make a DC 22 Charisma saving throw.

Regional Effects

• Clocks Keep Its Time. Within 6 miles of Aurumbrand, every mechanical timepiece, water clock, and bell tower drifts until it agrees with the colossus, regardless of the sun. Towns in range argue about noon.
• Shadows Fall Wrong. Within 6 miles, shadows point toward Aurumbrand rather than away from the sun. Creatures relying on shadows for navigation or concealment have disadvantage on Wisdom (Survival) checks to find their way, and Stealth checks made in shadow have disadvantage during daylight hours.
• The Unspent Hour. Once each dawn, everyone within 6 miles experiences the same minute twice. Spell durations, rituals, and any effect measured in rounds or minutes are extended by that minute, which has ruined at least three sieges and one wedding.