Xiphactinus

Huge Beast, Unaligned
Challenge 7 (2,900 XP) Proficiency Bonus +3

---

Armor Class 16 (natural armor)
Hit Points 136 (13d12 + 52)
Speed 0 ft., swim 60 ft.

“From the gloom below, a dagger-toothed maw erupts toward you—silent, sudden, and impossibly fast.”

---

Ability Scores

STR	DEX	CON	INT	WIS	CHA
22 (+6)	15 (+2)	18 (+4)	2 (–4)	13 (+1)	6 (–2)

---

Saving Throws

Dex +5, Wis +4

Skills

Perception +4, Stealth +5

Senses

Darkvision 60 ft., Passive Perception 14

Languages

—

Traits

---

Amphibious Hunter.

Xiphactinus can breathe underwater and hold its breath out of water for up to 1 hour. While on land, it has disadvantage on attack rolls and Dexterity checks.

---

Blood Frenzy.

The Xiphactinus has advantage on melee attack rolls against any creature that doesn’t have all its hit points.

---

Keen Smell.

The Xiphactinus has advantage on Wisdom (Perception) checks that rely on smell.

---

Swallow Whole.

When the Xiphactinus hits a Medium or smaller creature with its Bite, the target must succeed on a DC 16 Dexterity saving throw or be swallowed.

• A swallowed creature is blinded and restrained, has total cover from effects outside the Xiphactinus, and takes 14 (4d6) acid damage at the start of each of the Xiphactinus’s turns.
• If the Xiphactinus takes 30 or more damage on a single turn from a creature inside it, it must succeed on a DC 16 Constitution saving throw or regurgitate all swallowed creatures, who fall prone in a space within 10 feet.

---

Territorial Aggression (Recharge after a Short or Long Rest).

As a bonus action, the Xiphactinus enters a frenzied state for 1 minute. During this time:

• It has advantage on all attack rolls.
• It may make an additional Bite attack as a bonus action each turn.
• Opportunity attacks against it are made with disadvantage.

---

Actions

---

Multiattack.

The Xiphactinus makes two Bite attacks.

---

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target.

Hit: 26 (4d10 + 6) piercing damage. If the target is Medium or smaller, it must make a DC 16 Dexterity saving throw or be swallowed (see Swallow Whole).

---

Thrash Surge (Recharge 5–6)

The Xiphactinus dashes in a straight line up to 60 feet, moving through the spaces of creatures it chooses.

• Each creature in its path must succeed on a DC 17 Strength saving throw or take 18 (4d8) bludgeoning damage and suffer the following effects based on their physiology:
  • Creatures without a swim speed: Knocked prone.
  • Aquatic creatures with a swim speed: Stunned until the start of their next turn, representing loss of orientation.
• On a successful save, creatures take half damage and suffer no additional effects.

At the end of its movement, the Xiphactinus may make a Bite attack as a bonus action.

---

Tactics

The Xiphactinus is an ambush predator, striking with brutal speed and overwhelming force. It targets wounded prey to trigger Blood Frenzy, swallows isolated foes, and uses Thrash Surge to disrupt clustered groups. When outnumbered or injured, it triggers Territorial Aggression, becoming a relentless engine of destruction.

---

Legendary Variant (Optional Rule for Boss Encounters)

If the Xiphactinus is a central or apex predator in your setting, you may grant it Legendary Actions to enhance its lethality.

Legendary Actions

The Xiphactinus can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. It regains spent actions at the start of its turn.

• Lash of the Tail. The Xiphactinus makes a tail swipe. +9 to hit, reach 10 ft., one target. Hit: 11 (1d10 + 6) bludgeoning damage. The target must succeed on a DC 16 Strength saving throw or be knocked prone.
• Swift Pursuit. The Xiphactinus moves up to half its swim speed without provoking opportunity attacks.
• Surge Snap (Costs 2 Actions). The Xiphactinus makes a Bite attack. If the target is below half its hit point maximum, Swallow Whole activates on a hit without requiring a saving throw.

---

Xiphactinus

XP 3,200
N Huge animal
Initiative +4; Senses darkvision 60 ft., low-light vision, scent; Perception +12

---

DEFENSE

AC 21, touch 8, flat-footed 21 (–2 Dex, +13 natural)
hp 95 (10d8+50)
Fort +12, Ref +5, Will +4
Resistances cold 10 (see Cold-Blooded Predator)

---

OFFENSE

Speed 0 ft., swim 60 ft.
Melee bite +17 (2d10+12 plus grab)
Space 15 ft.; Reach 10 ft.
Special Attacks blood frenzy, swallow whole (Medium, AC 13, 15 hp, 1d8+6 bludgeoning plus 1d6 acid)

---

STATISTICS

Str 26, Dex 6, Con 21, Int 1, Wis 13, Cha 6
Base Atk +7; CMB +19 (+23 grapple); CMD 29 (can’t be tripped)
Feats Improved Initiative, Power Attack, Toughness, Lightning Reflexes, Improved Bull Rush
Skills Perception +12, Stealth +3, Swim +20
SQ amphibious, cold-blooded predator, surge strike

---

ECOLOGY

Environment warm aquatic (seas, coastal trenches, sunken canyons)
Organization solitary or pair
Treasure none (though valuables may be found near its kills or lair)

---

SPECIAL ABILITIES

---

Amphibious (Ex)
Although primarily aquatic, the Xiphactinus can breathe both air and water. It can survive on land for up to 1 hour before risking suffocation.

---

Blood Frenzy (Ex)
The Xiphactinus gains a +2 morale bonus on melee attack rolls against wounded creatures (those below their full hit points). This bonus stacks with other modifiers such as flanking or charging.

---

Cold-Blooded Predator (Ex)
Xiphactinus is instinctively drawn to warmer waters and resists cold. It gains cold resistance 10 and is immune to environmental cold. Magical cold slows the creature (as the slow spell) for 1 round unless it succeeds on a DC 15 Fortitude save.

---

Surge Strike (Ex) – Recharge 1d4 rounds
Once every 1d4 rounds, the Xiphactinus can surge up to 60 feet in a straight line without provoking attacks of opportunity. Each creature in its path must succeed on a DC 20 Reflex save or take 4d6 bludgeoning damage and be affected based on its movement type:

• Creatures without a swim speed: Knocked prone.
• Creatures with a swim speed: Staggered for 1 round (as they lose orientation).

If the surge ends adjacent to a creature, the Xiphactinus may make a single bite attack as a free action.

---

Swallow Whole (Ex)
A Xiphactinus that begins its turn with a Medium or smaller creature grappled in its jaws can attempt a second grapple check to swallow the creature whole. The swallowed creature takes 1d8+6 bludgeoning damage and 1d6 acid damage per round. It is trapped in the stomach (AC 13, 15 hp). A creature that cuts its way out with a slashing or piercing weapon escapes into the water; the opening closes immediately after. Only one creature may be swallowed at a time.

---

TACTICS

Before Combat
Xiphactinus lurks in deep waters or behind sunken terrain, using Stealth to ambush unsuspecting swimmers or boats. It prefers to strike at wounded prey to activate its blood frenzy.

During Combat
It opens with Surge Strike to scatter enemy formations and isolate targets. It prioritizes grappling and swallowing Medium or smaller foes, and will remain focused on wounded targets whenever possible.

Morale
Xiphactinus fights to the death when defending its territory. If summoned or magically compelled, it follows its orders until dismissed or destroyed.

---

DESCRIPTION

A sleek, nightmarish mass of muscle and fang, the Xiphactinus is a relic from ancient seas—an apex predator that swims with terrifying speed and devours its prey whole. Up to 20 feet long, its gaping maw is lined with dagger-like teeth, perfect for gripping struggling creatures mid-charge.

Sailors call it the Ironmaw, and fossils of these monstrous fish have been found with entire other fish preserved inside them, hinting at their reckless, all-consuming hunger. In fantasy settings, some believe these creatures are remnants of an older world—unchanged, undying, and waiting in the dark.

---

Variant: Drowned Xiphactinus (CR +1)

A Xiphactinus slain by dark magic or cursed waters may rise again as a terrifying undead predator.

• Type changes to undead (aquatic).
• Blood Frenzy is replaced by Create Spawn (drowned humanoids).
• Gains channel resistance +2 and a chilling aura (10-ft. radius, DC 17 Fortitude save or staggered 1 round).
• Immune to cold and natural exhaustion.

These haunted leviathans prowl cursed wrecks and drowned cities, forever reliving the moment of their own death in endless hunger.

Xiphactinus

A great fish at least as long as two tall humans. Its powerful torpedo-shaped body ends in a crescent-moon tail, while its ugly slab of a face has bulldog jaws crammed with spiky fangs.

Originally Posted by Cleon of the En World forums.

On this Thread

A Xiphactinus is a giant predatory fish that was a common apex predator of the shallow Cretaceous seas. They resemble an oversized fanged tarpon (Megalops), although they are not actually related to that fish. A typical adult specimen is 12-14 feet and weighs about 1200 pounds, the largest Xiphactinus can reach 20 feet long and weigh 5000 pounds or so.

Xiphactinus
Large animal (Aquatic)
Hit Dice	7d8+14 (45 hp)
Initiative	+1
Speed	Swim 60 ft. (12 squares)
Armor Class	15 (-1 Size, +1 Dexterity. +5 Natural), touch 10, flat-footed 14
Base Attack/Grapple	+5/+13
Attack	Bite +8 melee (1d8+6)
Full Attack	Bite +8 melee (1d8+6)
Space/Reach	10 ft./5 ft.
Special Attacks	Improved grab, swallow whole
Special Qualities	Low-Light Vision, Scent
Saves	Fort +7, Ref +6, Will +3
Abilities	Strength 18, Dexterity 13, Constitution 15, Intelligence 1, Wisdom 12, Charisma 2
Skills	Listen +5, Spot +5, Jump +16, Swim +12
Feats	Endurance, Diehard
Environment	Warm Aquatic
Organization	Solitary or school (2-20)
Challenge Rating	3
Treasure	None
Alignment	Always neutral
Advancement	8-11 HD (Large); 12-14 HD (Huge)
Level Adjustment	–

Combat

Xiphactinus are ferocious predators, attacking anything they think they can eat. A Xiphactinus only attacks prey small enough for it to swallow, since its jaws are designed for seizing victims, not tearing them into bite-sized chunks. Unfortunately, most Xiphactinus are large enough to swallow Medium-sized creatures such as adventurers. They are so voracious they sometimes swallow victims too dangerous for them, and are killed by their prey’s struggles in their stomach.

Improved Grab (Ex): To use this ability, a Xiphactinus must hit a smaller opponent with a bite attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it wins the grapple check, it establishes a hold and can swallow whole.

Swallow Whole (Ex): A Xiphactinus can try to swallow a grabbed opponent of a smaller size than itself by making a successful grapple check. Once inside, the opponent takes 1d8+4 points of crushing damage plus 4 points of acid damage per round. A swallowed creature can cut its way out by using a light slashing or piercing weapon to deal 15 points of damage to the stomach (AC 12). Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out. A Xiphactinus’s interior can hold 1 Medium, 4 Small, 16 Tiny, 64 Diminutive or 256 Fine opponents.

Skills

A Xiphactinus has a +8 racial bonus on any Swim check to perform some 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.