Ythorae the Skyfallen

Traits

• Legendary Resistance (3/Day). If Ythorae fails a saving throw, it can choose to succeed instead.
• Siege Monster. Ythorae deals double damage to objects and structures.
• Falling Still. Ythorae has not finished falling. It ignores difficult terrain, cannot be knocked prone or moved against its will, and any creature that ends its turn directly beneath Ythorae takes 22 (4d10) force damage as the air there gives way.
• Sky Without a Floor. Ythorae has advantage on saving throws against spells and other magical effects. Any spell of 6th level or lower cast within 120 feet of it that would create or shape light, air, or weather fails and is wasted.

Innate Spellcasting

Its spellcasting ability is Charisma (spell save DC 24, +16 to hit with spell attacks).

• Cantrips. Control Weather, Detect Magic, Earthquake, Gust of Wind, Levitate, Sunburst

Actions

• Multiattack. Ythorae makes two Falling Weight attacks and one Unmade Light attack.
• Falling Weight. Melee Weapon Attack: +18 to hit, reach 30 ft., one target. Hit: 6d10 + 10 bludgeoning damage. Ythorae does not strike so much as arrive. The target takes an extra 27 (6d8) thunder damage, and if it is Huge or smaller it is knocked prone and pushed up to 20 feet away.
• Unmade Light. Ranged Weapon Attack: +16 to hit, range 120/600 ft., one target. Hit: 8d8 radiant damage. A shaft of the wrong colour falls from somewhere above the sky. On a hit, the target cannot regain hit points until the end of its next turn, and any light source it carries is extinguished.
• The Note It Fell On (Recharge 5-6). Hit: 12d10 thunder damage. The target must succeed on a DC 25 Constitution saving throw, taking half as much damage on a successful one. Ythorae sounds the single sustained note it has been sounding since it fell. Each creature within 60 feet must make the save. A creature that fails is also deafened for 1 minute and cannot speak for that duration.

Bonus Actions

• Shed Glass. A sheet of Ythorae's substance breaks away and hangs in the air within 60 feet. It is an object with AC 18 and 40 hit points that provides three-quarters cover, and it detonates for 21 (6d6) slashing damage in a 10-foot radius when destroyed.
• Rise. Ythorae flies up to half its speed. It does not provoke opportunity attacks, and it may bring one creature it is grappling with it.

Reactions

• Displace the Air. The air where that creature is going is no longer there. The creature must succeed on a DC 25 Dexterity saving throw or have its movement end immediately and take 16 (3d10) force damage.
• Answering Note. Ythorae absorbs the sound. It takes no damage from the triggering effect, and its next Falling Weight attack before the end of its next turn deals an extra 27 (6d8) thunder damage.

Legendary Actions

• Weight.
• Drift. Ythorae moves up to half its flying speed without provoking opportunity attacks. Each creature whose space it passes through must succeed on a DC 25 Strength saving throw or be pushed 15 feet and knocked prone.
• Hold the Note. The falling note rises a semitone. Each creature within 60 feet of Ythorae that can hear must succeed on a DC 25 Constitution saving throw or take 27 (6d8) thunder damage and be deafened until the end of its next turn.

Lair Actions

• The Ground Forgets. A patch of ground 40 feet across stops being ground. Each creature standing on it must succeed on a DC 23 Dexterity saving throw or fall 30 feet upward, then take 21 (6d6) bludgeoning damage when the ground remembers and pulls it back down.
• Sky Below. For a moment everyone in the crater can see stars underfoot. Each creature that can see must succeed on a DC 23 Wisdom saving throw or be incapacitated until initiative count 20 of the next round.

Regional Effects

• Nothing Lands Right. Within 6 miles of the crater, thrown and dropped objects fall slightly slower than they should and never quite where they were aimed. Ranged weapon attacks made outdoors have disadvantage at long range, and no bird will overfly the region.
• The Held Note. Within 1 mile of the crater a single sustained tone is audible at all times, below hearing but not below noticing. Creatures that finish a long rest in the region must succeed on a DC 15 Wisdom saving throw or gain no benefit from it, having spent the night listening.