Tanystropheus

This bizarre creature looks like a snake with webbed feet on stubby legs. Its neck is almost half of its body length.

Originally Posted by Shade of the En World forums.
On this Thread

The tanystropheus is a strange semi-aquatic reptilian predator from the age of the dinosaurs.

A tanystropheus is about thirty feet long, and much of this is neck. Its hindquarters have extra mass to help balance the oversized neck. They are ambush predators, waiting in caves and underwater to grab passing prey. They feed mostly on fish, but they do grab larger prey, such as humanoids, on occasion.

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Tanystropheus
Huge animal
Hit Dice	6d8+24 (51 hp)
Initiative	+2
Speed	20 ft. (4 squares), Swim 40 ft.
Armor Class	14 (-2 size, +2 Dexterity, +4 natural), touch 10, flat-footed 12
Base Attack/Grapple	+4/+16
Attack	Bite +8 melee (1d8+6)
Full Attack	Bite +8 melee (1d8+6)
Space/Reach	15 ft./10 ft. (15 ft. with bite)
Special Attacks	Improved grab
Special Qualities	Low-Light Vision, Scent, stability
Saves	Fort +9, Ref +7, Will +2
Abilities	Strength 19, Dexterity 14, Constitution 18, Intelligence 1, Wisdom 11, Charisma 6
Skills	Hide +8, Listen +5, Spot +5
Feats	Alertness, Skill Focus (Hide), Weapon Focus (bite)
Environment	Warm aquatic and marsh
Organization	Solitary
Challenge Rating	4
Treasure	None
Alignment	Always neutral
Advancement	7-12 HD (Huge), 13-18 HD (Gargantuan)
Level Adjustment	–

COMBAT

A tanystropheus usually attacks from hiding, striking with its needle-sharp teeth and grabbing hold of its prey. It will then retreat, dragging its prey with it.

Extended Reach (Ex): The extremely long neck of a tanystropheus allows it to attack opponents up to 15 feet away. However, the small number of vertebrae make it less flexible, preventing it from attacking opponents within 5 feet.

Improved Grab (Ex): In order to use this ability, a tanystropheus must hit an opponent with a bite attack. It can then make a grapple check as a free action without provoking an attack of opportunity. If it gets a hold, it deals bite damage each round it maintains the grapple.

Stability (Ex): Due to the added weight in its hindquarters to balance its long neck, a tanystropheus gains a +4 bonus on ability checks made to resist being bull rushed or tripped when standing on the ground.

Skills: A tanystropheus has a +8 racial bonus on Hide checks.

A tanystropheus has a +8 racial bonus on any Swim check to perform a special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.

Originally appeared in Monster Manual II (1983).

Champ

Champ is the name given to a lake monster living in Lake Champlain. Native American tribes, the Iroquois and the Abenaki, talk of such a creature and celebrated its existence. The Abenaki gave it the name “Tatoskok.”

Tanystropheus

Large reptilian creature, unaligned

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Armor Class 14 (Natural Armor)
Hit Points 95 (10d10 + 40)
Speed 40 ft., swim 60 ft.

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STR	DEX	CON	INT	WIS	CHA
20 (+5)	14 (+2)	20 (+5)	2 (-4)	16 (+3)	6 (-2)

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Saving Throws: Dex +5, Con +7
Skills: Perception +5
Senses: Darkvision 60 ft., Passive Perception 15
Languages: Understands Aquatic (but cannot speak)
Challenge: 6 (2,300 XP)

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Traits

Long Neck

• It’s neck can extend a great distance, allowing it to attack from far away. When the Tanystropheus makes a melee attack with its bite, it can attack from up to 15 feet away instead of 5 feet.

Aquatic Ambusher

• It excels at ambushing prey from the water. It has advantage on attack rolls against creatures that are surprised or within 10 feet of a body of water.
• While submerged or in heavy vegetation, it can attempt to hide as a bonus action, even if it is in plain sight.

Swimmer’s Grace

• The Tanystropheus can move through water with remarkable speed and precision. It has advantage on Strength (Athletics) checks to swim and can dash through water without provoking opportunity attacks.

Camouflage

• The Tanystropheus has advantage on Stealth checks made in swampy, aquatic, or forested terrain due to its natural camouflage that helps it blend into the environment.

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Actions

Multiattack

• The Tanystropheus makes two attacks: one with its Bite and one with its Tail Slap.

Bite

Melee Weapon Attack: +7 to hit, reach 15 ft., one target.
Hit: 18 (2d10 + 4) piercing damage. If the target is a Medium or smaller creature, it must succeed on a DC 15 Strength saving throw or be grappled by the Tanystropheus. Until this grapple ends, the creature is restrained, and the Tanystropheus can’t bite another target.

Tail Slap

Melee Weapon Attack: +7 to hit, reach 10 ft., one target.
Hit: 15 (2d8 + 4) bludgeoning damage. On a critical hit, the target must succeed on a DC 15 Dexterity saving throw or be knocked prone.

Water Jet (Recharge 5–6)

• The Tanystropheus can expel a powerful burst of water from its mouth in a 30-foot cone. Each creature in that area must make a DC 15 Strength saving throw or be pushed 15 feet away and knocked prone. A creature that succeeds on the saving throw is not pushed but still falls prone if it is within 15 feet of the Tanystropheus.
• This ability is useful for pushing enemies into the water or knocking them out of advantageous positions.

Neck Strike (Recharge 5–6)

• The Tanystropheus can extend its long neck in an explosive attack. It makes a bite attack at advantage against one creature within 30 feet. On a hit, the target takes an additional 7 (2d6) bludgeoning damage as the Tanystropheus uses its neck like a battering ram.

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Legendary Actions

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

• Tail Lash (Costs 1 Action): The Tanystropheus makes a tail slap attack against one creature within 10 feet.
• Quick Lunge (Costs 2 Actions): The Tanystropheus moves up to 20 feet and makes a bite attack against a creature within reach.
• Ambush Strike (Costs 3 Actions): The Tanystropheus makes a bite attack with advantage against a creature within its reach that has not yet acted during combat.

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Tactics

• Ambush and Retreat: The Tanystropheus uses its Aquatic Ambusher trait to remain hidden in the water or thick vegetation, waiting to surprise its prey. It will often stay submerged, only revealing its long neck when it’s ready to strike.
• Use of Terrain: When it senses danger or fatigue, the Tanystropheus retreats into deep water, using its speed and Swimmer’s Grace to escape. It often lures enemies toward the water’s edge to capitalize on its superior movement and surprise attacks.
• Neck Strike: When surrounded or threatened by larger foes, the Tanystropheus will use Neck Strike to break free or inflict significant damage from a safe distance.
• Water Jet: To control the battlefield, the Tanystropheus uses Water Jet to disrupt enemies near the water, pushing them into dangerous positions or disorienting them with the powerful force.

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Reactions

Defensive Lunge

• When a creature hits the Tanystropheus with a melee attack, it can use its reaction to make a bite attack with advantage against the attacker.

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Environment

The Tanystropheus is typically found in marshes, coastal shores, or shallow lagoons. It thrives in areas with murky water and abundant plant life, where it can blend into its surroundings and ambush unwary travelers or prey.

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Motivation

The Tanystropheus hunts primarily for fish and other small aquatic creatures. It is a solitary and territorial predator, driven by an instinct to survive through stealth and ambush. It uses its long neck as both a tool for hunting and a weapon to defend itself against larger threats, making it an unpredictable and dangerous foe in the wilds of a forgotten world.