Olhydra

Princess of Evil Water Creatures, Princess of Evil Water, The Crushing Wave, The Well of Endless Anguish

Overview

Olhydra is the Princess of Evil Water. Sometimes known as the Crushing Wave, the Dark Tide, or the Well of Endless Anguish, she takes the form of a great wave, 20 feet high and 15 feet wide, with opalescent eyes. She prefers to remain in or near large bodies of water - seas, lakes, rivers, or sometimes great subterranean pools. When she needs to, she can surge onto dry land, moving much like a wave rushing up onto the shore, but only great anger or desperation would drive Olhydra to move more than a few hundred feet from her native element.
Olhydra surges forth tirelessly and relentlessly. She delights in creating dangerous and destructive manifestations of elemental water, especially maelstroms and floods. She is eager to assert her power by smashing any vessel that dares to venture into her realm, and lays waste to villages or towns established within her reach. Olhydra erodes that which she can’t batter and drown; she is patient, retreating in the face of adversity only to return stronger than before.
Of all the Princes of Elemental Evil, Olhydra is the one most interested in mortals. She recognizes that pirates and raiders who redden the waters with mortal blood (and occasionally send treasure-laden ships into her clutches) are agents of her hateful outlook, whether they know it or not. Consequently, Olhydra sometimes spares the worst sort of seafarers from her wrath, patiently waiting for the day when they deliver others into her power.

Olhydra’s Lair

The Princess of Evil Water is native to the Elemental Plane of Water, where she can be found in the black depths of vast seas or enthroned among jagged reefs. Olhydra waits for the chance to enter the Material Plane through elemental water nodes or when called by the proper rituals. Whether she is in her elemental domain or temporarily occupying a water node, Olhydra commands the waters around her and can shape them to her will.

Lair Actions

Olhydra can command the waters around herself to take lair actions on the Elemental Plane of Water, or in any elemental water node. On initiative count 20 (losing initiative ties), Olhydra uses her lair action to cause one of the following effects:

• Pools of water in the lair surge outward in a grasping tide. Any creature within 20 feet of such a pool must succeed on a DC 20 Strength saving throw or be pulled up to 20 feet into the water and knocked prone.
• Water within 120 feet of Olhydra becomes murky and opaque until initiative count 20 of the next round. A creature with darkvision can’t see through the water, and light can’t illuminate it.
• A freezing fog fills a 40-foot-radius sphere within 120 feet of Olhydra, lasting until initiative count 20 of the next round. Creatures and objects within or beyond the fog are heavily obscured. A creature that enters the freezing cloud for the first time on a turn or starts its turn there takes 3d6 cold damage.

Regional Effects

Olhydra’s presence in an elemental node creates a number of widespread effects - bad weather, strong tides, and increasing aggression from dangerous sea life.

• Violent downpours become frequent within 10 miles of the lair. A downpour occurs once every 2d12 hours, and lasts 1d4 hours. Downpours are so heavy that creatures moving over land travel at half speed.
• Within 5 miles of the lair, currents and tides are exceptionally strong and treacherous. Any ability checks made to safely navigate or control a vessel moving through these waters has disadvantage.
• Aquatic creatures that have an Intelligence score of 2 or lower within 1 mile of the lair must succeed on a DC 15 Wisdom saving throw when they enter the area. If the saving throw succeeds, the creature is frightened and attempts to leave the area, remaining frightened while within it. On a failure, the creature becomes highly aggressive and remains in the area for 24 hours. While in this state, the creature gains advantage on saving throws against charm and fear effects.
• Natural springs and pools within 1 mile of the lair form intermittent portals to the Elemental Plane of Water, allowing elemental creatures into the mortal world to dwell near those points.

If Olhydra is destroyed or banished back to her home plane, the regional effects fade over the next 1d10 days.

Olhydra CR: 18 (20,000 XP)

Huge elemental, neutral evil

Armor Class: 18

Hit Points: 324 (24d12 + 168)

Speed: 50 ft , swim: 100 ft

STR

21 +5

DEX

22 +6

CON

24 +7

INT

17 +3

WIS

18 +4

CHA

23 +6

Saving Throws: Str +11, Con +13, Wis +10

Damage Resistances: Lightning, as well as Bludgeoning, Piercing, and Slashing from nonmagical attacks

Damage Immunities: Acid, Cold, Poison

Condition Immunities: Charmed, Frightened, Paralyzed, Petrified, Poisoned, Prone, Restrained

Senses: Blindsight 120 feet, Passive Perception 14

Languages: Aquan

Challenge Rating: 18 (20,000 XP)

Empowered Attacks. Olhydra’s slam attacks are treated as magical for the purpose of bypassing resistance and immunity to nonmagical weapons.
Innate Spellcasting. Olhydra’s innate spellcasting ability is Charisma (spell save DC 20, +12 to hit with spell attacks). She can innately cast the following spells, requiring no material components:

• At will: wall of ice
• 3/day: ice storm
• 1/day: storm of vengeance

Legendary Resistance (3/Day). If Olhydra fails a saving throw, she can choose to succeed instead.
Magic Resistance. Olhydra has advantage on saving throws against spells and other magical effects.
Water Form. Olhydra can enter a hostile creature’s space and stop there. She can move through a space as narrow as 1 inch wide without squeezing.

Actions

Multiattack. Olhydra makes two slam attacks or two water jet attacks.
Slam. Melee Weapon Attack: +11 to hit, reach 10 feet, one target. Hit: 3d10 + 5 bludgeoning damage, and the target is grappled (escape DC 19). Olhydra can grapple up to four targets. When Olhydra moves, all creatures she is grappling move with her.
Water Jet. Ranged Weapon Attack: +12 to hit, range 120 feet, one target. Hit: 6d6 bludgeoning damage, and the target is knocked prone if it fails a DC 19 Strength saving throw.
Summon Elementals (1/Day). Olhydra summons up to three water elementals and loses 30 hit points for each elemental she summons. Summoned elementals have maximum hit points, appear within 100 feet of Olhydra, and disappear if Olhydra is reduced to 0 hit points.

Legendary Actions

Olhydra 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. Olhydra regains spent legendary actions at the start of her turn.
Crush. One creature that Olhydra is grappling is crushed for 3d10 + 5 bludgeoning damage.
Fling (Costs 2 Actions). Olhydra releases one creature she is grappling by flinging the creature up to 60 feet away from her, in a direction of her choice. If the flung creature comes into contact with a solid surface, such as a wall or floor, the creature takes 1d6 bludgeoning damage for every 10 feet it was flung.
Water to Acid (Costs 3 Actions). Olhydra transforms her watery body into acid. This effect lasts until Olhydra’s next turn. Any creature that comes into contact with Olhydra or hits her with a melee attack while standing within 5 feet of her takes 2d10 acid damage. Any creature grappled by Olhydra takes 4d10 acid damage at the start of its turn.

Alignment

Neutral Evil

Gender

Female