Gargantuan Elemental (Water)

Hit Dice: 36d8+216 (378 hp)

Initiative: +7 (Dex)

Speed: 20 ft, swim 90 ft

AC: 24 (-4 size, +7 Dex, +11 natural)

Attacks: Slam +35/+30/+25/+20 melee

Damage: Slam 2d10+16

Face/Reach: 20 ft by 20 ft/20 ft

Special Attacks: Spell-like abilities, water mastery, drench, vortex, capsize, summon water creatures

Special Qualities: Elemental, damage reduction 15/+3, SR 20, cold resistance 20, fire immunity, cold vulnerability

Saves: Fort +26, Ref +19, Will +16

Abilities: Str 32, Dex 24, Con 23, Int 20, Wis 18, Cha 18

Skills: Concentration +16, Intimidate +14, Knowledge (the planes) +15, Listen +29, Spot +29

Climate/Terrain: Any aquatic and underground

Organization: Solitary or troupe (Olhydra plus 1d3 Large or Huge water elementals, 1-2 sea hags, and 2-5 water weirds)
Challenge Rating: 17

Treasure: Double standard

Alignment: Always neutral evil

Advancement: —

Olhydra appears as a 35-foot tall humanoid composed of water. She has no discernable features (eyes, nose, etc.). She dwells in a great undersea castle on the Elemental Plane of Water.

COMBAT

Olhydra attacks with her slam attack and spell-like abilities in combat. If she becomes bored with combat or combat goes against her, she uses her summoning ability to call water creatures to her aid.

      Spell-Like Abilities: 3/day—acid fog, control water, ice storm and transmute rock to mud. These abilities are as the spells cast by a 20th-level sorcerer (save DC 14 + spell level).

      Water Mastery (Ex): Olhydra gains a +1 attack and damage bonus if both her and her opponent touch water. If she or her opponent is land bound, she suffers a –4 penalty to attack and damage. (These modifiers are not included in the statistics block).

      Drench (Ex): Olhydra’s touch puts out torches, campfires, exposed lanterns, and other open flames of nonmagical origin if these are of Huge size or smaller. She can dispel magical fire she touches as dispel magic cast by a 36th-level sorcerer.

      Vortex (Su): Olhydra can transform herself into a whirlpool once ever 10 minutes provided she is underwater, and remain in that form for up to 18 rounds. In vortex form, she can move through the water or along the bottom at her swim speed.

      The vortex is 5 feet wide at the base, up to 30 feet wide at the top, and 80 feet tall. She controls the exact height, but it must be at least 10 feet tall.

      Creatures of Huge or smaller size take damage when caught in the vortex and might be swept up by it. An affected creature must succeed at a Reflex save (DC 33) when it comes in contact with the vortex or take 2d8 points of damage. It must also succeed at a second Reflex save (same DC) or be picked up bodily and held suspended in the powerful currents, automatically taking damage each round. A creature that can swim is allowed a Reflex save each round to escape the vortex. The creature still takes damage, but can leave if the save is successful.

      Olhydra can eject any carried creatures whenever she wishes, depositing them wherever the vortex happens to be.

      If the vortex’s base touches the bottom, it creates a swirling cloud of debris. This cloud is centered on Olhydra and has a diameter equal to half the vortex’s height. The cloud obscures all vision, including darkvision, beyond 5 feet. Creatures 5 feet away have one-half concealment, while those further away have total concealment (see Concealment page 133 in the PHB). Those caught in the cloud must succeed at a Concentration check to cast a spell (DC 33).

      Capsize (Ex): Olhydra can surface under a boat or ship less than 20 feet long capsizes the vessel 100% of the time. She has a 75% chance to capsize a vessel from 20 to 60 feet long, and a 50% chance to capsize a vessel over 60 feet long.

      Summon Water Creatures (Sp): Once per day, Olhydra can automatically summon 1d3 Large or Huge water elementals, 3d4 sea hags, 2d4 water weirds, or 20-200 sahuagin.

      Elemental: Immune to poison, sleep, paralysis, and stunning. Not subject to critical hits.

      Cold Vulnerability (Ex): If Olhydra takes damage from a cold-based attack (i.e., it bypasses her cold resistance) she is slowed for a number of rounds equal to the caster’s level.