Adult Howling Dragon

Legendary Resistance (3/Day, or 4/Day in Lair). If the dragon fails a saving throw, it can choose to succeed instead.

Multiattack. The dragon makes three Rend attacks. It can replace one attack with a use of (A) Spellcasting to cast Phantasmal Killer or (B) Maddening Breath.

Rend. Melee Attack Roll: +14, reach 10 ft. Hit: 17 (2d8 + 8) Slashing damage plus 4 (1d8) Thunder damage.

Howling Breath (Recharge 5–6).Constitution Saving Throw: DC 21, each creature in a 60-foot Cone. Failure: 66 (12d10) Thunder damage. Success: Half damage.

Spellcasting. The dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 21, +13 to hit with spell attacks):

At Will: Detect Magic, Phantasmal Killer, Mind Spike
3/Day Each: Synaptic Static,

Maddening Breath. Wisdom Saving Throw: DC 21, each creature that isn’t currently affected by this breath in a 60-foot Cone. Failure: The target has Disadvantage on Wisdom-based D20 Tests and subtracts 3 (1d6) from its damage rolls. It repeats the save at the end of each of its turns, ending the effect on itself on a success. After 1 minute, it succeeds automatically.

Legendary Action Uses: 3 (4 in Lair). Immediately after another creature’s turn, the dragon can expend a use to take one of the following actions. The dragon regains all expended uses at the start of each of its turns.

Stagger. Charisma Saving Throw: DC 21, one creature the dragon can see within 120 feet. Failure: 10 (3d6) Psychic damage, and the target has the Incapacitated condition until the start of the dragon’s next turn. Failure or Success: The dragon can’t take this action again until the start of its next turn.

Qu'est-ce que c'est? The dragon uses Spellcasting to cast Phantasmal Killer.

Pounce. The dragon moves up to half its Speed, and it makes one Rend attack.