Kel-Arasat, the Sundial Colossus

Traits

• Legendary Resistance (3/Day). If Kel-Arasat fails a saving throw, it can choose to succeed instead.
• Magic Resistance. Kel-Arasat has advantage on saving throws against spells and other magical effects.
• Immutable Form. Kel-Arasat is immune to any spell or effect that would alter its form.
• Sunlit Aegis. At the start of each of its turns, if Kel-Arasat is in an area of bright light or under an open sky by day, it regains 20 hit points. If it starts its turn in magical darkness, it instead has disadvantage on attack rolls until the start of its next turn.
• Siege Monster. Kel-Arasat deals double damage to objects and structures. It treats a wall as difficult terrain rather than an obstacle.

Spellcasting

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

• At will. Light, Guidance, Thaumaturgy
• 3/day each. Dispel Magic (3rd level), Plane Shift (7th level), Sunbeam (6th level)

Actions

• Gnomon Blade. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 36 (4d12 + 10) slashing damage. The target takes an extra 22 (5d8) radiant damage. A creature struck by the Gnomon Blade casts no shadow until the end of its next turn and cannot benefit from being heavily obscured during that time.
• Solar Lash. Ranged Weapon Attack: +16 to hit, range 120/240 ft., one target. Hit: 37 (6d8 + 10) radiant damage. A whip of compressed noon light. On a hit, the target must succeed on a DC 24 Constitution saving throw or be blinded until the end of its next turn.
• Shadowfall (Recharge 5–6). Kel-Arasat sweeps its shadow across the battlefield in a 60-foot cone. Damage: 67 (15d8) radiant damage. Each creature in that area must make a DC 24 Dexterity saving throw, taking 67 (15d8) radiant damage on a failed save, or half as much on a successful one. A creature that fails is also pushed 30 feet away and knocked prone as the hour it stands in is dragged forward. Nonmagical objects in the area that are not being worn or carried are aged one century.

Bonus Actions

• Advance the Hour. Kel-Arasat rotates its dial one hour. Every creature it can see that is suffering a condition with a duration ends or advances that duration by one round, Kel-Arasat’s choice for each creature.

Reactions

• Cast No Shadow. Trigger: When a creature Kel-Arasat can see hits it with a melee attack. Kel-Arasat steps into its own shadow and out again, teleporting up to 30 feet to an unoccupied space it can see. The triggering attack misses if the new space is beyond the attacker’s reach.

Legendary Actions

Kel-Arasat, 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. Kel-Arasat regains spent legendary actions at the start of their turn.

• Meridian Step. Kel-Arasat teleports up to 60 feet to an unoccupied space it can see that is in bright light. It may make one Gnomon Blade attack on arrival if it teleports to a space within 20 feet of a creature.
• Sweep the Dial. Kel-Arasat drags its shadow in a 30-foot line. Each creature in that line must succeed on a DC 24 Strength saving throw or be pushed 20 feet and knocked prone.
• Toll the Hour (Costs 2 Actions) (Costs 2 Actions). Kel-Arasat strikes the Meridian Ring. Each creature of its choice within 60 feet must succeed on a DC 24 Constitution saving throw or take 27 (6d8) thunder damage and be stunned until the end of its next turn. On a success, the creature takes half damage and is not stunned.

Lair Actions

• Noon Without Warning. A shaft of hard white light falls through the ceiling onto a 20-foot-radius circle Kel-Arasat can see. Each creature within a 20-foot radius must make a DC 24 Dexterity saving throw, taking 28 (8d6) radiant damage on a failed save, or half as much damage on a successful one.
• The Shadow Moves. The great shadow of the gnomon sweeps across the floor. Its 60-foot-long, 10-foot-wide path becomes difficult terrain until the next lair action, and any creature that ends its turn in that path has disadvantage on its next attack roll as the hour under its feet shifts.

Regional Effects

• The Hour Is Kept. Within 6 miles of Kel-Arasat, every clock, candle-mark, and water-glass agrees exactly, and no creature can be surprised by the passage of time — spell durations, torches, and rations are tracked with perfect precision by everyone in the region, whether they want that knowledge or not.
• Shadows Point Home. Every shadow within 6 miles falls toward Kel-Arasat regardless of the light source. Travelers who follow their own shadow cannot become lost on the way to the colossus, and cannot navigate away from it without a DC 20 Wisdom (Survival) check made each hour.