Undead Lake Monster (3.5e Monster)

A titanic sea serpent rises from the lake, its flesh is gray and molted, hanging limply off its bones in places as it stares down at you with sunken, lifeless eyes

The undead lake monster is a rare sight. It is an ancient, gargantuan, undead water serpent with grayish-green skin and a huge mouth lined with needle-sharp teeth. Its scaly hide is reminiscent of the skin of a zombie, rotten-smelling and marked with rents and gaps though which pale white bones show. When swimming on the surface, it often appears to be a head followed by a series of rounded humps.

Combat
This monster never leaves its lake, but it will attack any creature that comes close to the shore. Before combat has been announced, if the monster has seen intruders near the lake's shore it will try to lure them closer for an ambush. The creature lures the curious and foolhardy into range by appearing briefly in the center of the lake, then disappearing under water, only to appear moments later within striking range. Despite its undead state, the monster is extremely supple and can twist and curve its long body around, moving quickly through the water. It can coil its body underwater and strike like a snake up to 50 feet from the shore or up to 60 feet above the surface.

Improved Grab : To use this ability, the Undead Lake Monster must hit with its bite attack. It can then attempt to start a grapple as a free action without provoking attacks of opportunity. If it wins the grapple check, it establishes a hold and can attempt to swallow the foe the following round (see below).

Swallow Whole : An Undead Lake Monster can try to swallow a grabbed opponent of Medium or smaller size by making a successful grapple check. Once inside, the opponent takes 1d8+11 points of crushing damage plus 8 points of acid damage per round from the Monster's necrotic gizzard. A swallowed creature can cut its way out by using a light slashing or piercing weapon to deal 25 points of damage to the gizzard (AC 16). Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out. A Gargantuan Undead lake monster's interior can hold 2 Huge, 8 Large, 32 Medium-size, or 128 Small or smaller creatures.

Breath Weapon : Three times a day this undead creature can exhale a highly toxic cloud of sickly yellow vapor that is 40 feet long and 20 feet wide and high, producing the same effect as that of the spell Cloudkill as cast by a 14th level Wizard. The breath lingers in the air, moving slowly with the breeze and sinking into depressions for four rounds before dissipating.

Bellow : Should the battle turn against it, the monster can emit a frightening, unearthly cry. This is a sound-based ability invoke the effects of the 4th-level wizard spell fear (usable three times per day). This affects all creatures within 100 feet who do not make a successful saving throw vs. spell.

Undead Traits: An Undead Lake Monster is immune to mind-affecting effects, poison, sleep, paralysis, stunning, disease, death effects, necromantic effects, and any effect that requires a Fortitude save unless it also works on objects. It is not subject to critical hits, subdual damage, ability damage, ability drain, energy drain, or death from massive damage. An Undead Lake Monster cannot be raised, and resurrection works only if it is willing.

Habitat/Society
Such monsters are considered unique, yet there are some who speculate that there is more than one “serpent of the depths” in any world. Some claim to have sighted two separate sets of humps breaking the surface of a lake at once. Other sages maintain that the undead lake monster has an unnatural brood of little serpents, and that its attacks upon any who approach its lake are the equivalent of a mother protecting her young, but it is unclear how an undead creature could give birth to young.

The monster’s watery lair is said to be filled with the treasures of those it has pulled down to their deaths, but the lake which houses such a creature is always hundreds of feet deep, so it’s unlikely that any of that supposed treasure could ever be recovered. Even if items are somehow found, any armor or weapons in the hoard (unless magically protected) are likely to be rusted and useless.

Ecology
Because it is undead, the lake monster has no natural life span. If killed, it will not provide any useful products. Its hide is tough enough to use for (leather) armor or a shield, but it has an oppressive stench that will force a character trying to use it to make hourly Fortitude saves ((DC 15)) to avoid nausea (-1 penalty to attack rolls for an hour).