Unleashing the Hydra's Full Potential
Looking to get started with Hydra? Start Here
The Hydra stands as one of D&D's most iconic and terrifying monsters — a massive, multi-headed serpent born of chaos and corruption, whose very presence poisons the land and whose heads multiply when severed. These writhing abominations represent primal hunger and impossible regeneration, the kind of nightmare that grows stronger the more you fight it.
Both the 2014 and 2024 D&D Hydra do a great job of capturing the iconic multiple heads and regeneration mechanics. The reactive regrowth ability is elegant: sever a head with 25+ damage, and at the start of the hydra's turn, two new heads sprout in its place. It's thematic, it scales well, and it creates that signature "oh no, we made it worse" moment at the table.
But here's the missed opportunity: that's all the hydra brings. Beyond the heads and bites, there's nothing else mechanically interesting going on. No acidic blood spraying when you sever a head. No toxic breath that spreads disease across the battlefield. No unbridled aggression that makes the creature more dangerous when wounded.
That's why we gave the Hydra the comprehensive upgrade it deserves:
- 2 unique Statblocks (Hydra, Foulblood Hydra) with dozens of variants each
- Custom Hydra Powers that emphasize regeneration, acidic attacks, and territorial corruption
- Flavorful and table-ready Hydra Encounter Ideas and Hydra Adventure Ideas
- Enhanced lore that makes these creatures feel like living environmental disasters
2 Enhanced Hydra Statblocks
As usual for Foe Foundry, we created multiple monster statblocks, each with dozens of unique combinations of powers. You can click on the dice to re-roll the stats and try a new loadout, or check out the Generator to customize the monster yourself.
These statblocks work perfectly for swamp-based campaigns and deadly wilderness encounters, especially when combined with ready-to-go Hydra Encounters and Hydra Adventures.
| Statblock | CR | Description |
|---|---|---|
| Hydra | 8 | The classic five-headed terror of the swamps with regenerating heads and acidic blood |
| Foulblood Hydra | 12 | A legendary variant infected with demonic ichor, capable of raising the dead and cursing its victims |
Hydra
The classic Hydra is a CR 8 nightmare that combines overwhelming offense with terrifying resilience. Five heads mean five bite attacks per turn, and each severed head triggers an acidic blood spray before regrowing into two new heads.
Hydra
Summoned with Foe FoundryHuge Monstrosity (Hydra)
AC 16 Initiative +5 (15)
HP 178 (17d12 + 68)
Speed 40 ft., swim 40 ft.
| Mod | Save | ||
|---|---|---|---|
| Str | 20 | +5 | +5 |
| Dex | 14 | +2 | +2 |
| Con | 18 | +4 | +4 |
| Mod | Save | ||
|---|---|---|---|
| Int | 10 | +0 | +0 |
| Wis | 12 | +1 | +4 |
| Cha | 9 | -1 | -1 |
Skills Perception +7
Resistances Acid
Immunities Blinded, Charmed, Deafened, Frightened, Stunned, Unconscious
Senses Darkvision 60 ft., Passive Perception 17
CR 8 (3,900 XP; PB +3)
Traits
Cauterize. When the hydra takes Acid, Fire, or Cold damage, it must make a DC 15 Constitution saving throw. On a failed save, it cannot regain hitpoints until the end of its next turn.
Multi-Headed. The hydra has five heads. It can make as many Opportunity Attacks as it has heads.
Regrowth. At the start of its turn, if the hydra's Severed Head reaction triggered last turn, it heals 20 hitpoints. If it healed, it generates two new heads.
Actions
Multiattack. The hydra makes one attack for each of its heads. It may replace one attack with a use of its Fearsome Roar.
Flesh-Dissolving Bites. Melee Weapon Attack: +8 to hit, reach 5ft., one target. Hit 9 (1d8 + 5) piercing damage and 2 (1d4) acid damage. On a hit, the target must make a DC 16 Constitution saving throw or become Poisoned until the end of its next turn.
Fearsome Roar (1/day). The hydra targets up to eight creatures they can see within 60 ft. Each must make a DC 16 Wisdom saving throw. On a failure, the affected target is Frightened for 1 minute (save ends at end of turn) and must immediately use its reaction, if available, to move their speed away from the hydra avoiding hazards or dangerous terrain if possible.
Reactions (One Per Head)
Severed Head. When the hydra takes 20 or more damage from an attack and has at least two heads, one of its heads is severed. Each other creature in a 10 foot emanation must make a DC 16 Dexterity saving throw, taking 12 (5d4) acid damage on a failed save. The hydra may use its Regrowth ability at the start of its next turn.
Foulblood Hydra
When a Hydra consumes enough demonic flesh, it becomes infected with fell ichor. The Foulblood Hydra is a CR 12 legendary monstrosity that combines all the classic hydra abilities with cursed wounds and the power to raise slain victims as undead thralls.
Foulblood Hydra
Summoned with Foe FoundryHuge Monstrosity (Fiend*, Hydra)
AC 18 Initiative +10 (20)
HP 287 (23d12 + 138)
Speed 40 ft., swim 40 ft.
| Mod | Save | ||
|---|---|---|---|
| Str | 22 | +6 | +10 |
| Dex | 14 | +2 | +2 |
| Con | 22 | +6 | +10 |
| Mod | Save | ||
|---|---|---|---|
| Int | 11 | +0 | +0 |
| Wis | 12 | +1 | +5 |
| Cha | 9 | -1 | -1 |
Skills Perception +9, Survival +5
Resistances Acid
Immunities Blinded, Charmed, Deafened, Frightened, Stunned, Unconscious
Senses Darkvision 60 ft., Passive Perception 19
CR 12 (8,400 XP; PB +4)
Traits
Black Blood. When the hydra takes piercing or slashing damage, it splashes nearby creatures with black ichor. Each non-demon creature within 10 feet takes 4 Acid damage and its movement speed is halved until the end of its next turn. This ability activates only once per turn.
Cauterize. When the hydra takes Acid, Fire, or Cold damage, it must make a DC 15 Constitution saving throw. On a failed save, it cannot regain hitpoints until the end of its next turn.
Multi-Headed. The hydra has five heads. It can make as many Opportunity Attacks as it has heads.
Regrowth. At the start of its turn, if the hydra's Severed Head reaction triggered last turn, it heals 20 hitpoints. If it healed, it generates two new heads.
Legendary Prowess (3/day). The hydra can choose to succeed on a saving throw or ability check instead of failing. When it does so, it takes 15 force damage.
Actions
Multiattack. The hydra makes one attack for each of its heads.
Flesh-Dissolving Bites. Melee Weapon Attack: +10 to hit, reach 5ft., one target. Hit 10 (1d8 + 6) piercing damage and 2 (1d4) acid damage. On a hit, the target must make a DC 18 Constitution saving throw or become Poisoned until the end of its next turn.
Bonus Actions
Cursed Wounds. Immediately after hitting with an attack, the hydra converts all of that attack's damage to necrotic damage and forces the target to make a DC 18 Charisma save. On a failure, the target is cursed and its maximum hit points are reduced by the necrotic damage taken. The target dies and reanimates as a Zombie under the control of the hydra if this damage leaves it with 0 hit points.
Reactions (One Per Head)
Severed Head. When the hydra takes 20 or more damage from an attack and has at least two heads, one of its heads is severed. Each other creature in a 10 foot emanation must make a DC 18 Dexterity saving throw, taking 15 (6d4) acid damage on a failed save. The hydra may use its Regrowth ability at the start of its next turn.
Bestial Rampage (1/day). When the hydra is reduced to half its health or lower, it moves up to 30 feet without provoking opportunity attacks and makes a melee attack against another target in its rage.
Legendary Actions (3)
Charge. The hydra moves up to half its speed and makes an Flesh-Dissolving Bites attack.
Replenish. The hydra gains 10 temporary hitpoints. It can't take this action again until the start of its next turn.
10 Powers That Make Hydras Unforgettable
These powers transform the Hydra from a simple damage-dealer into a dynamic battlefield controller that grows more dangerous as combat progresses, punishes melee attackers, and creates memorable tactical challenges.
Hydra Heads
Hydra Heads
Traits
Multi-Headed. The hydra has five heads. It can make as many Opportunity Attacks as it has heads.
Regrowth. At the start of its turn, if the hydra's Severed Head reaction triggered last turn, it heals 20 hitpoints. If it healed, it generates two new heads.
Cauterize. When the hydra takes Acid, Fire, or Cold damage, it must make a DC 15 Constitution saving throw. On a failed save, it cannot regain hitpoints until the end of its next turn.
Reactions (One Per Head)
Severed Head. When the hydra takes 20 or more damage from an attack and has at least two heads, one of its heads is severed. Each other creature in a 10 foot emanation must make a DC 16 Dexterity saving throw, taking 12 (5d4) acid damage on a failed save. The hydra may use its Regrowth ability at the start of its next turn.
Used by Foulblood Hydra (CR 12), Hydra (CR 8)
Hydra Heads is the signature ability that makes hydras iconic. Picture the moment when a barbarian's greatsword severs one of those writhing necks — everyone in melee range must dodge the spray of acidic blood, and next round the stump erupts with two new heads snapping and hissing.
Wild Instinct
Wild Instinct
Bonus Actions
Wild Instinct (1/day). The wolf identifies the creature with the lowest Strength score that it can see. It then uses Dash towards that creature.
Used by Basilisk, Dire Bunny, Wolf, Hydra, Manticore
Wild Instinct perfectly captures the predatory nature of a territorial apex predator. The hydra identifies the weakest-looking prey and charges directly toward them, creating panic among backline casters and archers. This ability ensures the hydra doesn't just stand in one spot trading blows — it actively hunts the party's vulnerable members, forcing defenders to intercept or risk watching their wizard get surrounded by five snapping jaws.
Fearsome Roar
Fearsome Roar
Actions
Fearsome Roar (1/day). The chimera targets up to eight creatures they can see within 60 ft. Each must make a DC 15 Wisdom saving throw. On a failure, the affected target is Frightened for 1 minute (save ends at end of turn) and must immediately use its reaction, if available, to move their speed away from the chimera avoiding hazards or dangerous terrain if possible.
Used by Balor, Berserker, Hydra, Ogre, Orc, Owlbear
With Fearsome Roar, the Hydra can scatter a tightly grouped party in an instant. Five heads unleashing a synchronized bellow creates a moment of pure terror — up to eight creatures must save or flee, triggering opportunity attacks from those multiple heads. This ability shines when the party tries to surround the hydra, turning their tactical advantage into a death trap as frightened PCs trigger multiple attacks of opportunity while fleeing.
Toxic Breath: Blinding Sickness
Toxic Breath: Blinding Sickness
Traits
Blinding Sickness (Disease). This creature can inflict the Blinding Sickness disease: An infected creature's mind is gripped by pain and its eyes turn milky white. The creature has disadvantage on Wisdom checks and Wisdom saving throws and is Blinded.
Actions
Toxic Breath (Recharge 5-6). The ghoul exhales toxic gas in a 15-foot cone. Each creature in that area must make a DC 12 Constitution saving throw. On a failure, the creature takes 7 (2d6) poison damage and is Poisoned for 1 minute (save ends at end of turn). If a creature fails this save three times, it becomes afflicted by Blinding Sickness.
Used by Hydra, Ghoul, Mage, Vrock, Zombie
When the Hydra exhales Toxic Breath: Blinding Sickness, it transforms the battlefield into a zone of debilitating disease. The 30-foot cone deals immediate poison damage, but the real threat is the Blinding Sickness disease — multiple failed saves leave victims blinded, turning what should be an organized party into a collection of stumbling, helpless targets. This creates pressure to end combat quickly before the disease stacks become overwhelming.
Toxic Breath: Mindfire
Toxic Breath: Mindfire
Traits
Mindfire (Disease). This creature can inflict the Mindfire disease: The creature's mind becomes feverish. The creature has disadvantage on Intelligence checks and Intelligence saving throws, and the creature behaves as if under the effects of the Confusion spell during combat.
Actions
Toxic Breath (Recharge 5-6). The ghoul exhales toxic gas in a 15-foot cone. Each creature in that area must make a DC 12 Constitution saving throw. On a failure, the creature takes 7 (2d6) poison damage and is Poisoned for 1 minute (save ends at end of turn). If a creature fails this save three times, it becomes afflicted by Mindfire.
Used by Hydra, Mage, Vrock, Zombie
Toxic Breath: Mindfire specifically targets the party's spellcasters and tacticians. Once infected, the Mindfire will wreak chaos on the party as they stumble around in confusion.
Bestial Rampage
Bestial Rampage
Reactions
Bestial Rampage (1/day). When the wolf is reduced to half its health or lower, it moves up to 30 feet without provoking opportunity attacks and makes a melee attack against another target in its rage.
Used by Basilisk, Hydra, Manticore
Bestial Rampage ensures the hydra becomes even more dangerous when bloodied. The moment the hydra drops to half health, it immediately repositions without provoking opportunity attacks and makes an additional attack. This reactive ability keeps players on their toes — they can't safely assume the hydra will stay put just because they've surrounded it, and the "bloodied" marker that usually signals victory becomes a trigger for renewed aggression.
Cursed Wounds
Cursed Wounds
Bonus Actions
Cursed Wounds. Immediately after hitting with an attack, the ghost converts all of that attack's damage to necrotic damage and forces the target to make a DC 14 Charisma save. On a failure, the target is cursed and its maximum hit points are reduced by the necrotic damage taken. The target dies and reanimates as a Zombie under the control of the ghost if this damage leaves it with 0 hit points.
Used by Hydra, Spirit, Skeleton
The Foulblood Hydra's Cursed Wounds ability turns every successful attack into a potential death sentence. By converting damage to necrotic and reducing maximum hit points, the hydra creates escalating pressure that healing can't fully counter. But the real horror comes when a character drops to zero hit points and they immediately reanimate as a zombie under the hydra's control, forcing their former allies to fight them or watch helplessly as their friend attacks them.
DM Tip
Any ability that bypasses Death Saving Throws should be telegraphed to the party. This prevents players from feeling caught in a "gotcha" and also ratchets up the tension. Players tend to not be that worried about dropping to 0 because they feel "safe" behind the Death Saving Throws.
Black Blood
Black Blood
Traits
Black Blood. When the balor takes piercing or slashing damage, it splashes nearby creatures with black ichor. Each non-demon creature within 10 feet takes 6 Acid damage and its movement speed is halved until the end of its next turn. This ability activates only once per turn.
Used by Balor, Cultist, Hydra, Merrow
Black Blood punishes melee attackers with automatic acid damage and movement reduction. Every time someone hits the Foulblood Hydra with a slashing or piercing weapon, everyone within 10 feet gets splashed with corrosive ichor. This creates a zone of death around the hydra — melee characters must weigh every attack against the guaranteed retaliation, and the slowed movement makes escape difficult once you've engaged.
DM Tip
This ability drips flavor, but sometimes you want to encourage melee combat instead of punishing it. Use abilities like Bestial Rampage and Wild Instinct to target ranged attackers as well.
Feeding Frenzy
Feeding Frenzy
Bonus Actions
Feeding Frenzy. The wolf moves up to 30 feet without provoking opportunity attacks. If it ends the movement next to a target that has lost half its hit points or more, it may make an attack against that target.
Used by Basilisk, Dire Bunny, Wolf, Hydra, Manticore
Feeding Frenzy represents the hydra at its most savage — when it smells blood in the water, all five heads converge on a single wounded target with devastating focus. By granting advantage and bonus damage against bloodied enemies, this ability turns the first character to drop below half health into a priority target. The tactical message is clear: stay healthy or become the hydra's exclusive focus.
Table-Ready Hydra Encounters
Want to unleash a regenerating nightmare on your party? We've created table-ready Hydra Encounters and Hydra Adventures that showcase these creatures' unique blend of overwhelming offense and impossible resilience.
My personal favorites include:
While navigating a fetid swamp, the party rests on a small island covered in reeds that is actually a Hydra's five heads resting on its submerged body. The island begins to shift and heave as the hydra awakens.
Robed Cultists chant around a chained Hydra, throwing bound prisoners into its reach. The hydra has been starved and driven mad. The cultists use its acidic blood in rituals.
These encounters emphasize the hydra as both an ambush predator and a territorial force that corrupts everything around it. The creature works perfectly as a swamp guardian, a cultist's living weapon, or a territorial nightmare that must be navigated around rather than confronted directly.
Want more? Check out the full collection of Hydra Encounters and Hydra Adventures.
Environmental Corruption
One of the most underutilized aspects of hydras is their corrupting presence. The Foe Foundry version emphasizes this: a hydra doesn't just live in a swamp — it poisons the swamp. Fish float belly-up, crops fail within a mile, livestock birth two-headed mutants. This corruption makes the hydra more than a combat encounter; it becomes an environmental disaster that affects entire regions.
Use this when building adventures: the party might fight a hydra to save a village's water supply, investigate mysterious mutations affecting local wildlife, or track the source of a spreading blight. The hydra becomes a problem that manifests long before the party enters combat, building dread and emphasizing the stakes.
Make Your Hydra Unforgettable
The Hydra has always been one of D&D's most iconic monsters — a perfect representation of the "grows stronger when wounded" archetype. But without proper powers and tactics, it risks becoming a repetitive slog where players just hack away at heads until someone remembers to use fire.
With enhanced powers, varied statblocks, and encounter ideas that emphasize environmental corruption and tactical depth, these new Hydra variants become memorable centerpiece monsters. Whether you're running a swamp-based adventure, need a territorial nightmare guarding an ancient ruin, or want to showcase a legendary creature that tests your party's resource management and tactical thinking, these regenerating terrors are ready to multiply.
Summon Your Own
Explore both Hydra statblocks, encounter ideas, and adventure prompts below—or summon a random Hydra and watch the heads multiply.
Ready to face the regenerating nightmare? Summon a Hydra