Ancient Copper Dragon

+7

Arcana: The monster's treasure hoard features magic items with the noted theme. The Dungeon Master's Guide details treasure hoards appropriate for each theme.

If the dragon fails a saving throw, it can choose to succeed instead.

5/DAY

The dragon makes three Rend attacks. It can replace one attack with a use of (A) Slowing Breath or (B) Spellcasting to cast Mind Spike (level 5 version).

Melee Attack Roll: +15, reach 15 ft. Hit: 19 (2d10 + 8) Slashing damage plus 9 (2d8) Acid damage.

Dexterity Saving Throw: DC 22, each creature in an 90-foot-long, 10-foot-wide Line. Failure: 63 (14d8) Acid damage. Success: Half damage.

D5

Constitution Saving Throw: DC 22, each creature in a 90-foot Cone. Failure: The target can't take Reactions; its Speed is halved; and it can take either an action or a Bonus Action on its turn, not both. This effect lasts until the end of its next turn.

The dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 21):

• At will: Detect Magic, Mind Spike (level 5 version), Minor Illusion, Shapechange (Beast or Humanoid form only, no Temporary Hit Points gained from the spell, and no Concentration or Temporary Hit Points required to maintain the spell)
• 1/day each: Greater Restoration, Major Image, Project Image

The Ancient Copper Dragon can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The Ancient Copper Dragon regains spent legendary actions at the start of its turn.

3/TURN

Charisma Saving Throw: DC 21, one creature the dragon can see within 120 feet. Failure: 31 (9d6) Psychic damage. Until the end of its next turn, the target rolls 1d8 whenever it makes an ability check or attack roll and subtracts the number rolled from the D20 Test. Failure or Success: The dragon can't take this action again until the start of its next turn.

The dragon uses Spellcasting to cast Mind Spike (level 5 version). The dragon can't take this action again until the start of its next turn.

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

Copper dragons typically inhabit multichamber caves and renovated ruins. The region containing an adult or ancient copper dragon's lair is changed by its presence, creating the following effects:

Chatty Critters: Tiny Beasts magically gain the ability to speak and understand Draconic while within 6 miles of the lair.

Giggle Fits: Whenever a creature other than the dragon and its allies is within 1 mile of the lair and rolls a 1 on a D20 Test, it must succeed on a DC 15 Wisdom saving throw or have the Incapacitated condition until the end of its next turn, as it is wracked with laughter.

If the dragon dies or moves its lair elsewhere, these effects end immediately.