Undead Dragon

Gargantuan undead (dragon), chaotic evil

Armor Class 22 (natural armor)
Hit Points 546 (28d20 + 252)
Speed 40 ft., fly 80 ft., swim 40 ft.

STR	DEX	CON	INT	WIS	CHA
30 (+10)	14 (+2)	29 (+9)	18 (+4)	17 (+3)	28 (+9)

Saving Throws Dexterity +10, Constitution +17, Wisdom +11, Charisma +17
Skills Insight +11, Perception +19
Senses darkvision 60 ft., passive Perception 29
Languages –
Challenge 26 (90,000 XP)

Special Traits

• • Legendary Resistance (3/day). If the undead dragon fails a saving throw, it can choose to succeed instead.
  • Regeneration. The undead dragon regains 30 hit points at the start of its turn if it has at least 1 hit point and isn’t in sunlight. If the undead dragon takes radiant damage or damage from holy water, this trait doesn’t function at the start of the undead dragon’s next turn.
  • Soul Consumption. When a creature dies within 30 feet of the undead dragon, that creature must succeed on a DC 18 Wisdom saving throw or that creature’s soul is torn from its body and pulled into the undead dragon’s gaping maw. The undead dragon gains a number of temporary hit points equal to the dead creature’s Hit Dice. Creatures that die in this manner can only be restored to life by a true resurrection or wish spell.
  • Spellcasting. The undead dragon is an 18th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 25, +17 to hit with spell attacks). It can cast the following spells:
    • Cantrips (at will): chill touch, fire bolt, mage hand, mending, prestidigitation, ray of frost
    • 1st level (4 slots): burning hands, magic missile, protection from evil and good, thunderwave
    • 2nd level (3 slots): blindness/deafness, flaming sphere, ray of enfeeblement, scorching ray
    • 3rd level (3 slots): blink, dispel magic, fireball, gaseous form, gust of wind, haste
    • 4th level (3 slots): confusion, fire shield, greater invisibility, wall of fire
    • 5th level (3 slots): arcane hand, cone of cold, mislead, wall of stone
    • 6th level (1 slot): chain lightning, circle of death, irresistible dance
    • 7th level (1 slot): forcecage, prismatic spray
    • 8th level (1 slot): control weather, maze
    • 9th level (1 slot): foresight, time stop

Actions

• • • Multiattack. The undead dragon can use its Frightful Presence and make three attacks: one with its bite and two with its claws.
    • Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 26 (3d10 + 10) piercing damage plus 21 (6d6) necrotic damage. The target’s hit point maximum is reduced by an amount equal to the necrotic damage taken, and the undead dragon regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.
    • Claws. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 23 (3d8 + 10) slashing damage. The target is grappled (escape DC 24) if the undead dragon isn’t already grappling a creature, and the target is restrained until this grapple ends.
    • Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage.
    • Frightful Presence. Each creature of the undead dragon’s choice that is within 120 feet of the dragon and aware of it must succeed on a DC 24 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the undead dragon’s Frightful Presence for the next 24 hours.
    • Change Shape. The undead dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (the dragon’s choice). In a new form, the dragon retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.
    • Breath Weapons (Recharge 5-6). The undead dragon uses one of the following breath weapons.
    • Fire Breath. The undead dragon exhales fire in a 90-foot cone. Each creature in that area must make a DC 24 Dexterity saving throw, taking 82 (15d10) fire damage on a failed save, or half as much damage on a successful one.
    • Weakening Breath. The undead dragon exhales gas in a 90-foot cone. Each creature in that area must succeed on a DC 24 Strength saving throw or have disadvantage on Strength-based attack rolls, Strength checks, and Strength saving throws for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Legendary Actions

the undead 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 undead dragon regains spent legendary actions at the start of its turn.

• • • Detect. The undead dragon makes a Wisdom (Perception) check.
    • Tail Attack. The undead dragon makes a tail attack.
    • Wing Attack (Costs 2 Actions). The undead dragon beats its wings. Each creature within 15 ft. of the undead dragon must succeed on a DC 25 Dexterity saving throw or take 20 (3d6 + 10) bludgeoning damage and be knocked prone. The undead dragon can then fly up to half its flying speed.