Metallic Greatwyrm

Gargantuan Dragon (Metallic), Typically Lawful Good
Armor Class 22 (natural armor)
Hit Points 565 (29d20 + 261)
Speed 60 ft., burrow 60 ft., fly 120 ft., swim 60 ft.
STR
30 (+10)
DEX
16 (+3)
CON
29 (+9)
INT
21 (+5)
WIS
22 (+6)
CHA
30 (+10)
Saving Throws Dex +11, Con +17, Int +13, Cha +18
Skills Insight +14, Perception +22, Persuasion +18
Damage Immunities acid (copper), cold (silver), fire (brass and gold), or lightning (bronze)
Condition Immunities charmed, frightened, poisoned
Senses truesight 120 ft., passive Perception 32
Languages Common, Draconic
Challenge 28 (120000 XP)     Proficiency Bonus +8
Legendary Resistance (4/Day).
Metallic Awakening (Recharges after a Short or Long Rest).
Unusual Nature.
ACTIONS
Multiattack.
Bite.
Claw.
Tail.
Breath Weapon (Recharges 5-6).
Elemental Breath.
Sapping Breath.
Change Shape.
LEGENDARY ACTIONS
Attack.
Wing Attack (Costs 2 Actions).
MYTHIC ACTIONS
Bite.
Shattering Roar (Costs 2 Actions).

This full creature's stat block is not available (not OGL).

Fizban´s Treasury of Dragons
Metallic Greatwyrm