Crashing Wave Hydra

Huge monstrosity, chaotic evil

Physical Description

The Crashing Wave Hydra is a massive five-headed beast that embodies the fury of storm-tossed seas. Its serpentine necks rise from a muscular torso, each head crowned with razor-sharp fangs that crackle with electrical energy. Its scales shimmer with an iridescent blue-green hue, appearing to undulate like the surface of the ocean even when still. Lightning arcs between its heads during moments of agitation, and the water around it churns violently in response to its presence.

"The sea itself trembled at its coming, waves roiling and churning in fear."

Lore

The Crashing Wave Hydra is a living storm of fang and lightning. Tales of its destructive rampages strike fear into the hearts of even veteran sailors. Its mere presence agitates the ocean, calling forth churning waves and waterspouts.

Maritime Terror Sailors speak of the Crashing Wave Hydra in hushed tones, telling stories of entire fleets lost to its fury. The creature is said to be drawn to ships during storms, using the natural chaos of the weather to mask its approach until it's too late. Some coastal communities make regular sacrifices to the sea, hoping to appease the hydra and keep it from approaching their shores.

Living Storm Some scholars theorize that the Crashing Wave Hydra isn't truly alive in the conventional sense, but rather a manifestation of the ocean's rage given physical form. Its ability to manipulate water and generate lightning suggests a deep connection to elemental forces beyond mere biological capability.

Survivor's Account

"That thing...it was like the sea was its eyes and ears. Could sense us even through the hull of the ship. Its lightning tore through the water, flashed through our veins. Felt like my blood was on fire..." — Sole survivor of the merchant vessel Windward Promise

Stats

• Armor Class: 16 (natural armor)
• Hit Points: 195 (17d12 + 85)
• Speed: 30 ft., swim 60 ft.

STR	DEX	CON	INT	WIS	CHA
23 (+6)	12 (+1)	21 (+5)	2 (-4)	10 (+0)	7 (-2)

• Saving Throws: Dex +5, Con +9
• Damage Immunities: lightning
• Senses: darkvision 60 ft., passive Perception 10, currentsense 120 ft.
• Languages: —
• Challenge: 12 (8,400 XP)

Multiple Heads. The hydra has five heads. While it has more than one head, the hydra has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Whenever the hydra takes 25 or more damage in a single turn, one of its heads dies. If all its heads die, the hydra dies.

At the end of its turn, it grows two heads for each of its heads that died since its last turn, unless it has taken fire damage since its last turn. The hydra regains 10 hit points for each head regrown in this way.

Wakeful. While the hydra sleeps, at least one of its heads is awake.

Currentsense. The hydra can detect prey by sensing minute shifts in water currents from up to 120 feet away. Nowhere is safe from its lightning-laced fury.

Lightning Breath (Recharge 2-3). The hydra exhales lightning in a 60-foot line that is 5 feet wide. Each creature in the line must make a DC 17 Dexterity saving throw, taking 54 (12d8) lightning damage on a failed save, or half as much damage on a successful one.

Electro-Shock (Recharge 4-5). The hydra releases a surge of electricity in a 30-foot radius centered on itself. Each creature within range must make a DC 17 Constitution saving throw. On a failed save, a creature takes 22 (4d10) lightning damage, and can't take reactions until the start of its next turn. On a successful save, the creature takes half as much damage.

Supercharge (Recharge 6). As a bonus action, the hydra shrouds itself with lightning, overcharging its body. For 1 minute, its bite attacks deal an extra 10 (3d6) lightning damage on a hit. Creatures that touch the hydra or hit it with a melee attack while it is overcharged take 5 (1d10) lightning damage.

Lightning Lash. When reduced to half its hit points or fewer, the hydra lashes out with bolts of lightning in rage. The hydra automatically hits each creature within 60 feet of it with Lightning Breath, no attack roll or saving throw required.

Multiattack. The hydra makes as many bite attacks as it has heads.

Bite. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 15 (2d8 + 6) piercing damage.

Crashing Wave (Recharge 5-6). The hydra creates a 15-foot tall wave that crashes onto one target ship within 60 feet of it. That ship must succeed on a DC 16 Dexterity saving throw or take 22 (4d10) bludgeoning damage and have its speed reduced by 10 feet until the end of its next turn as the wave batters it.

Legendary Actions

The hydra 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 hydra regains spent legendary actions at the start of its turn.

Detect (1). The hydra makes a Wisdom (Perception) check.

Attack (2). The hydra makes a bite attack or uses its Lightning Breath.

Churning Waters (3). The water within 60 feet of the hydra becomes difficult terrain until the end of its next turn.

Lair Actions

On initiative count 20 (losing initiative ties), the hydra takes a lair action to cause one of the following effects:

• The hydra creates a wave that batters all ships within 60 feet of it. Each ship must succeed on a DC 15 Dexterity saving throw or take 15 (3d10) bludgeoning damage and have its speed halved until the start of the hydra's next turn.

• A bolt of lightning erupts from the water within 60 feet of the hydra. The hydra chooses a point it can see within range and each creature within 5 feet of that point must make a DC 15 Dexterity saving throw, taking 22 (4d10) lightning damage on a failed save, or half as much damage on a successful one.

• Fog rises from the water. The area within 60 feet of the hydra is heavily obscured until the end of its next turn.

Tactics

The Crashing Wave Hydra begins combat by using its Supercharge ability if available, then positions itself to catch as many enemies as possible in its Lightning Breath or Electro-Shock abilities. It prioritizes attacking ships with its Crashing Wave ability, attempting to slow or disable vessels to prevent escape. The hydra uses its legendary actions strategically, creating difficult terrain with Churning Waters to hamper enemy movement while using its multiple heads to attack different targets. When reduced to half health, it unleashes its Lightning Lash ability, often retreating temporarily underwater to recover before resuming its assault.

"When the waters begin to churn without wind, when lightning flashes beneath clear skies—pray to whatever gods you hold dear, for the Crashing Wave Hydra has found you."