Last Updated on January 22, 2023
The hydra. Ever since Disney’s Hercules and probably before, the hydra has been one of the more famous monsters to come from Greek mythology. Originally called the Lernaean Hydra, the beast has become synonymous with an inability to be killed and endless heads that regrow after every attempt to cut them down.
The creature is no less mighty in D&D 5e, where its many heads retain their ability to regenerate and throw off the action economy.
What Is a Hydra in DnD 5e?
The hydra is a mythical beast with multiple regenerative heads, one that heroes have slain in countless narratives, and D&D 5e is no different. The creature has a deadly hunger, and in the right hands, it can be a terrifying and overwhelming foe.
However, in the wrong hands, it’s possible to make the hydra fall a little flat or be presented as something other than it is. For example, some people consider the hydra to be a type of dragon, but, in fact, the creature is a waterborne beast.
Additionally, at this point, many people know of the hydra’s weakness to fire, but DMs can often effectively neuter a hydra encounter by making fire too easily accessible or by ignoring the creature’s instincts to put itself out.
If you want to know how to make the hydra a powerful and threatening creature that makes full use of its multi-headed attack strategy, this article is for you. If you’re a player who isn’t sure how you’re going to face an upcoming hydra in your next session, I’ll be detailing all the ways you can outshine even Hercules himself.
Stats & Abilities
Of course, we’ve all heard about the hydra from Greek mythology, but what can a hydra from D&D 5e do?
- STR 20 (+5), DEX 12 (+1), CON 20 (+5), INT 2 (-4), WIS 10 (+0), CHA 7 (-2)
- AC: 15 (natural armor)
- Hit points: 15d12+75 (172 avg)
- Speed: 30 ft., swim 30 ft.
- Skills: Perception (+6)
- Senses: 60 ft. of Darkvision and 16 Passive Perception
- Challenge Rating: 8
Additionally, the hydra has several abilities. Most of these are related to its multiple heads, but it also has a Hold Breath ability as befits its waterborne nature that lets it hold its breath for up to 1 hour.
It is also Huge sized, taking up a 15×15-ft. square on a usual D&D grid.
The hydra has several abilities (Multiple Heads, Reactive Heads, Wakeful, Multiattack, and Bite) that are all directly related to its heads.
Its main ability is Multiple Heads. By default, a hydra has five heads. As long as it has at least two heads, it has advantage on saving throws that would impose the blinded, charmed, deafened, frightened, stunned, and unconscious conditions upon it, which is quite a suite.
If the hydra takes 25 or more points of damage in a single turn, a head dies. Notably, this appears to imply that only one head can die per turn. It’s also important to note that the rules specify turns here, not rounds, so (with the exception of unlikely abilities that allow damage to be dealt on another’s turn) each party member is responsible for an attempted head-chopping.
At the end of the hydra’s turn, if it has not taken fire damage since its last turn, it grows two additional heads per head that died since its last turn. It also regenerates 10 hit points for each head that grows like this.
The hydra dies if all its heads die, and presumably if it hits 0 hit points. However, it is ambiguous whether or not the hydra would come back to life if it was supposed to regrow heads while dead. This quasi-resurrection could make for an added challenge, but you should generally assume that once it reaches 0 hit points, the hydra will stay at 0 hit points.
Multiple heads also mean multiple attacks. The hydra’s core Bite attack has a +8 to hit, a 10-foot reach, and does 1d10+5 (10 avg) piercing damage. However, the hydra also has Multiattack, allowing it to make as many attacks per turn as it has heads. You can imagine how deadly that can become!
These attacks also scale to opportunity attacks. The hydra’s Reactive Heads ability allows it an extra reaction per head that it can use for opportunity attacks.
Finally, the hydra’s extra heads guarantee that at least one head is always awake, meaning the hydra can never be caught totally unconscious (unless via magic or poison).
A hydra’s tactics are not complex mostly because the creature has an Intelligence of 2 and is driven primarily by an insatiable hunger. It doesn’t have specific desires that would lead it to plan, and its size, strength, and regenerative powers mean the average hydra has little to no fear.
That might make it seem terrifying (and it can be), but a lack of fear can actually be much more of a detriment than an advantage. True, the hydra will usually have no use for fear, but when it faces competent adventurers, often with supernatural abilities, a little fear is a good thing.
The hydra’s tactics consist only of attacking the nearest threats as much as possible. It has little intuition about the benefits of focus fire, and as such, a DM can actually modulate the difficulty of a hydra encounter by altering how much it spreads around damage.
The hydra’s instincts will lead it to try to intimate and frighten its enemies. Those who flee suffer the wrath of opportunity attacks. A good strategy for DMs looking to make good use of these opportunity attacks is to use all but one or two opportunity attacks at the first available opportunity. You may only get one chance a round to use these, so you better use them!
The attacks you save are mostly there to ensure you can still punish movement without disengaging.
Finally, I recommend that DMs run hydras with an instinctive fear of fire. Those wielding fire will be attacked the hardest, and should the hydra be set on fire, its priorities will temporarily switch from attacking and devouring to submerging itself in the nearest body of water or, failing that, putting out the fire by some other means.
A hydra is not intelligent, but it should instinctually know that fire can prevent it from regeneration. Notably, a hydra cannot distinguish the source of a spell like Fireball (simply because it lacks the ability to draw that kind of nonlinear connection), so magical attacks will not raise its ire.
To sum up, a hydra should:
- Attack whoever’s closest with its heads, ideally spreading out the damage evenly.
- Only focus on a specific enemy if that enemy is visibly wielding fire.
- Immediately attempt to put itself out if set on fire.
- Try to intimidate and frighten its enemies into fleeing so its heads can make attacks of opportunity.
A hydra is a simple, powerful creature. It lacks intelligence, has powerful advantages, and requires a specific approach to defeat. In other words, it is a creature against which careful planning and tactics work especially well. I would go so far as saying that a completely classless group of 1-15 soldiers could, with proper coordination and planning, take down a hydra by themselves.
The obvious ingredient here is fire. A hydra’s regeneration means you cannot simply damage it until it dies. Do too much damage in a single turn, and the hydra will grow more powerful. While growing a new head does restore some health, the greater danger is that the hydra will be able to do more damage, and if you are forced to retreat, it will retain those heads indefinitely.
Magical means of fire can be risky. They burn spell slots, and many have attack rolls that can miss. Your party’s priority should be to do at least one point of fire damage each round. You don’t need to do a lot of fire damage, so low-level spells are fine, but you also mustn’t let RNG let the hydra get away with growing another head, so backup sources of fire are a must.
Nonmagical means of fire offer the compelling advantage of greater flexibility in deployment. Burning arrows, tar, firebombs, and the like can all be effective and can be delivered by a variety of means. If the party doesn’t have to waste an action doing fire damage because the hydra is covered in flaming tar, all the better. Enterprising players might also ask their DMs if intense sources of heat, like thermite (which is technically not fire), can still be effective.
Moreover, a hydra’s own awareness of fire and low Intelligence score means it can be readily manipulated. If you can lure the hydra to a prepared area, you can use lines of fire (tar or some other flammable substance laid out in a line) to corral the hydra, trap it, or even protect weaker allies behind flames. A hydra might not treat a wall of fire like an impassable obstacle, but it will surely make it hesitate.
In addition, the hydra’s damage cap of 25 damage per turn means that strategies that rely on a higher number of low-damage turns are more effective. For the party, hiring a crossbow contingent is a good way of getting chip damage on a hydra; the party acts like a tank while the crossbows stay safe at a distance. This is also why a contingent of 10-15 soldiers can be as effective as a high-level party.
Aside from tactics oriented around fire, a hydra’s other weakness is its low Intelligence. Baiting a hydra to leave a body of water that might prove troublesome for your fire plans is definitely doable — your druid could turn into a magically hastened goat to lure the hydra to your prepared ground.
A low Intelligence also means a high susceptibility to illusions. Using illusions as bait to block the hydra’s path or to trick the creature into an environmental hazard such as a pit are all extremely feasible.
Finally, never ever trigger the hydra’s opportunity attacks. It already has enough damage potential; you don’t want to add to it. Remember that the hydra’s reach is 10 feet, not 5 feet, so if you decide to get close to the monster, you need to have a way to use the Disengage action or otherwise prevent opportunity attacks before leaving.
Spreading out can help with this. If moving closer to any specific enemy would put a hydra out of attacking range to another enemy, it probably won’t bother. You can use this positioning tactic to keep squishier allies out of the hydra’s danger zone.
Running a Hydra Encounter
Knowing what a hydra can do and how a hydra does it might seem like a good start for running a hydra encounter, but for DMs looking to run a hydra, there are a few other tactical and flavor considerations to keep in mind.
There’s a lot to take into account when running a hydra encounter. Chief among those is the environment. Is your hydra terrorizing a local village? Will your players face the hydra in the village? On the road? Perhaps at a swamp or in a nearby lake?
Your players might not even be encountering the hydra in a combat scenario at all. Perhaps the creature is the pet of a nearby powerful wizard, or perhaps someone has decided to try to create an infinite food source out of the hydra’s regenerating heads.
Whatever the case may be, running a hydro counter requires you to understand the local resources that a player, or indeed the hydra itself, might be able to use.
This is because of the hydra’s primary weakness — fire. The availability of fire and especially the availability of water or other sources of fire suppression will be key to deciding whether or not the players can win the day.
For example, if the players end up fighting the hydra in a swamp, they might find that the recommended tactic above of continuous flame is not nearly as effective since the hydra can continuously put itself out by just submerging briefly.
On the other hand, if the players are forced to fight the hydra in a Coliseum-type environment or after the hydra escapes a wizard’s control search, the fire might be much harder to come by. That might even be dangerous, for example, if the surrounding area is extremely flammable.
The tactical terrain can also be significant. For example, if the players are forced to move often, triggering the hydras opportunity attacks, the fight can become much more dangerous and quickly.
Assessing and balancing these factors is therefore key to giving the players a challenge. Make it too easy, and the hydra will be no more than any other generic monster with a couple of extra attacks per round. On the other hand, make it too hard, and suddenly your eighth-level party might not be suitable for taking on what has turned into a true monstrosity.
So much for the tactical considerations.
Flavoring the Myth
I also strongly recommend focusing on the lower implications for hydra. These creatures should not be used for simple random encounters; rather, they are significant foes even for higher-level parties simply because of their mythological status in minds of your actual players.
Take the time to demonstrate the effects of the hydra on the local wildlife. They are rapacious consumers and will happily eat to extinction everything in the area before moving on. Describe the blight that a hydra imposes on the land.
You can also emphasize the human cost. Have the party run into victims of the hydra or those who have heard of its terror and have been forced to simply not travel or travel more difficult routes. This has the added benefit of letting the players know what they might face (if you like that sort of thing).
Finally, you can heighten the terror of a hydra by leaning into its mechanical advantages. Roll separately for each attack the hydra makes, letting the players feel that their four or five actions are easily matched by the hydra’s many heads.
In the wild, hydras will sometimes resort to attacking themselves should food become too scarce. Such an action will result in a hydra with more heads than usual since after a long rest the hydra will be back to full health but retain its heads. You can always increase the difficulty of a hydra encounter by presenting the party with a hydra with seven heads, or 10, or any number.
Leaning into the mechanical advantage of a 20-headed hydra can be very effective.
Of course, you never want to take up too much time simply rolling dice and taking playing hours away from the actual players, but making sure your players are aware of how long a hydras turn takes just because of the sheer number of attacks it makes can be a more effective way to impart upon them the danger than simply giving them a higher number for total damage than usual.
Using these techniques, you can demonstrate the power and effects of a hydra, making the monster live up to the reputation it has in your players’ minds. When they slay it, the victory will be all the sweeter.
Not To Be Confused With…
If you’re looking for content for D&D 5e hydras, you might come across a fascinating homebrew variant called the false hydra. As you might expect, the false hydra is not really the same thing as a hydra. In fact, other than the fact that the false hydra has multiple heads, this homebrew creature bears little resemblance to the D&D 5e waterborne monster.
That said, the false hydra is one of the most interesting homebrew creatures out there, and I definitely recommend giving it a deeper look.
The monster has pale white flesh, and instead of reptilian heads, it grows human heads attached to long necks. Each head emits a “song,” an eerie sound that makes anyone who hears it forget entirely that the creature exists, even when looking directly at it.
The song also makes you forget the creature’s victims. A town infested by a false hydra operates without a care in the world, slowly forgetting about their loved ones and families as the false hydra devours them.
Because the creature is homebrew, there’s no official stat block out there, but there are a lot of interesting ideas about how to use the creature most effectively. A good place to continue to read about the false hydra is the blog that originally came up with the concept. You can find the original here.
From the Lernaean Hydra of mythology to the false hydra of homebrew, the multi-headed reptile has been inspiring monster designs for centuries.
In D&D 5e, the hydra is no less iconic. Its multiple heads and regenerative abilities afford it unique opportunities for stacking the action economy deck in its favor. Its weakness to fire only undermines it when the players can use fire appropriately, which can be trickier than you might think.
Moreover, the hydra is one of D&D’s more mythological monsters. While many monsters are drawn from myths and legends, the hydra is well known, occupying an eminent position in the cultural consciousness. That alone makes it a great option to give the players a challenge, not to mention its interesting implementation as mentioned earlier.
Whether you’re facing down a hydra as an adventurer, running a hydra encounter as a DM, or trying to take advantage of a hydra’s infinite regeneration, you now know everything you need to know about hydras.
- About Author
- Latest Posts
Growing up I spent most of my time reading, so when I first started playing RPGs in middle school and got a copy of DnD 3.5’s rules I loved their collaborative take on storytelling. These days I like to use RPGs to develop my creative problem-solving skills as well.