Hydra

Version 0.15: This article may not be up to date for the latest stable release of Crawl.

For a list of all dragon-like creatures, see list of dragons.

hydra D
HP	54-91
HD	13
XP	976
Speed	10 (swim: 60%)
AC	0
EV	5
Will	52
Attack1	18 (bite: plain) per head
Resistances	rPois+, rDrown, rWater
Vulnerabilities	None
Habitat	Amphibious
Intelligence	Reptile
Uses	Uses nothing
Holiness	Natural
Size	Big
Type	hydra, hydra
Flags	Cold-blooded Regenerates

A great and nightmarish lacertilian beast. It has many heads, and the potential to grow many more! Hitting it with any cutting weapon bigger than a dagger or a quick blade risks lopping a head off, which, considering hydra's unique biology, is not what you want unless the blade is hot enough to cauterize the wound. Even a troll's claws may be enough to rip hydra heads.

Useful Info

Hydras are notoriously dangerous melee monsters found most often in the Lair and the Swamp. They begin life with 4-8 heads, but grow two more and heal significantly whenever they lose one. This usually happens when a player or trap deals slashing damage to it. Careless use of claws, axes, long blades, short swords, and cutlasses can result in prolonged and deadly combat. Any such attack that deals 1-3 damage has a 50% chance of removing a head, while 4+ will always do so.

Fortunately, there are ways to hurt them without them growing stronger. Blunt and piercing weapons injure them as normal, and flaming edged weapons will remove heads and cauterize the wound, preventing the normal regrowth. Ranged weapons and spells also function without issue.

Hydras cannot fly, but they swim quickly through water. Lava will effectively stop them, however.

While exploring the bottom floor of the Swamp, beware the Lernaean hydra. This unique hydra is much more lethal than normal.

Tips & Tricks

• Hydras with additional heads only get more attacks per turn, not more HD, XP, or MR.
• Hydras max out at 20 heads, at which point they get 20 individual melee attacks per turn. Don't let this happen.
• If you manage to get a hydra to 0 heads, it dies instantly regardless of how much HP it had left.
• The Summon Hydra spell lets you call a friendly 4-9 headed hydra to fight for you, but only for a brief time.
• They have poison resistance, so poison and Mephitic Cloud won't work.
• If attempting to escape, remember that hydras cannot open doors nor see invisible.
• Here are some tips for edged-weapon users:
  • Use a flaming weapon to not only avoid regrowth and healing, but to reduce the hydra's damage output with each hit. Generally, faster weapons work better for this purpose, as they give they hydra less time to gnaw on you between swings. However, most characters are unlikely to have found multiple flaming weapons by the time they reach the Lair -- use whatever you have.
  • Use a non-edged weapon of the same skill, such as:
    • Maces and Flails: Not an issue.
    • Short Blades: Use a Quick blade or dagger. Fighting a hydra with a dagger is still not recommended unless you have Stabbing bonuses. Invisibility is quite useful here, since they neither see nor sense it.
    • Polearms: Use a spear, trident, or demon trident.
    • Staves: Use a quarterstaff or enhancer staff.
    • Axes and Long Blades: There are no safe options. Use spells, wands, or a weapon you aren't skilled in (only recommended with high AC, berserking, or other buffs).
    • Unarmed Combat: Only characters with Claws 3 are at risk of severing heads. Ghouls and Felids only have one level of claws, but Trolls will have to find another way.
  • Invocations:
    • Makhleb: Greater Servants can easily kill hydras.
    • Beogh: Smite works, but at a high piety cost.
    • Elyvilon: Hydras are natural beasts, and can be pacified easily.
    • Lugonu: With high Invocations, you may be able to send hydras to the Abyss.
    • Qazlal: Blasting hydras with Upheaval works, though it chews through piety quickly.
  • Spells:
    • Conjurations: Most level 3+ Conjurations can kill a hydra in 3-6 hits, and even level 2's can soften them up significantly with enough time. Hydras leave poisonous corpses, so Ignite Poison will hurt it effectively and reliably.
    • Summonings: 4-7 ice beasts can easily kill a hydra, though a hydra with a high number of heads may require more.
    • Transmutations: Use Ice Form or unarmed Statue Form. Spider Form does not remove heads, but is generally less effective than Ice or Statue Form.
  • Wands: Even at low Evocations, a wand of fire, wand of cold, wand of draining, or wand of fireball can usually kill a hydra in 2-5 hits. This is a safe course of action for most characters.

The following methods do not work:

• Polymorph: Hydras have high HD, and often turn into even toughter monsters. Storm dragons are a particularly common result.
• Low-Skill Archery: Hydras regenerate quickly; any method which relies on whittling down its HP will likely fail.
• Stair dancing: Climbing up or down stairs next to a hydra will give it a few free hits, which is possibly all it needs to kill you.
• Berserk With an Edged Weapon: While you may be able to deal more damage than the hydra can heal per hit, its damage output will be growing, and ending your berserk slowed and wounded next to an even stronger hydra than you started with is not ideal.
• Haste, when in the Swamps: Hydras' speed advantage in water will mean you probably cannot outrun them.

Undead Hydras

Hydra corpses that are raised as zombies or skeletons will have the same number of heads as the corpse; zero-headed corpses cannot be raised this way. Hydra simulacra may have more or less heads. In either case, you can slice their heads off as with normal hydras, but they will never grow back, even if a non-flaming weapon is used. Note that hydra simulacra can have horrifyingly high damage output if you lack cold resistance: +13-38 cold damage per head.

Spectral hydras created with Death Channel will have the same number of heads as the hydra when it died, but these can't be cut off.

Any of these undead hydras can be found as enemies throughout the dungeon, especially in the pestilence ending of the Swamp.

History

Prior to 0.12 hydras were not cold-blooded creatures, except the Lernaean hydra.

In 0.16, all Short Blades will do piercing damage, meaning short swords and rapiers will no longer remove heads.