Elemental Water Dragon

Huge elemental, neutral evil

Armor Class

Hit Points

310 (27d12 + 135)

Speed

40 ft., fly 60 ft., swim 80 ft.

STR

25 (+7)

DEX

24 (+7)

CON

21 (+5)

INT

16 (+3)

WIS

14 (+2)

CHA

19 (+4)

Damage Immunities

poison

Damage Resistances

acid; bludgeoning, piercing, and slashing from nonmagical weapons

Condition Immunities

exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious

Senses

blindsight 60 ft., darkvision 120 ft., passive Perception 24

Saving Throws

Dex +13, Con +11, Wis +8, Cha +10

Skills

Arcana +9, Nature +9, Perception +14, Stealth +13

Languages

Aquan, Common

Challenge

17 (18,000 XP)

Freeze. If the elemental water dragon takes cold damage, it partially freezes; its speed is reduced by 20 feet until the end of its next turn.

Innate Spellcasting. The dragon’s innate spellcasting ability is Charisma (spell save DC 18, +10 to hit with spell attacks). It can cast the following spells, requiring no material components:

At will: create or destroy water
3/day: control water
1/day each: control weather, plane shift

Legendary Resistance (3/day). If the dragon fails a saving throw, it can choose to succeed instead.

Siege Monster. The dragon deals double damage to objects and structures.

Actions

Multiattack. The dragon can make three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 18 (2d10 + 7) piercing damage.

Claw. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 7) slashing damage.

Tail. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 16 (2d8 + 7) bludgeoning damage.

Steam Breath (Recharge 5–6). The dragon exhales a 60-foot cone of superheated steam that spreads around corners. Creatures within the area must make DC 19 Dexterity saving throws, taking 63 (18d6) fire damage on a failed saving throw, or half as much on a successful one. Being underwater does not provide resistance to this effect.

Bonus Actions

Drench. The elemental water dragon can extinguish any one nonmagical flame or one magical flame created by a 5th level or lower spell it can see within 15 feet of it.

Legendary Actions

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

Detect. The dragon makes a Wisdom (Perception) check.

Tail Attack. The dragon makes a tail attack.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 19 Dexterity saving throw or take 14 (2d6 + 7) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.