Hydra

Version 0.31: This article may not be up to date for the latest stable release of Crawl.

For a list of all reptiles, see list of reptiles and amphibians.

hydra D
HP	47-96
HD	13
XP	972
Speed	10 (swim: 60%)
AC	0
EV	5
Will	60
Attack1	18 (bite: plain)
Resistances	rPois+ rDrown
Vulnerabilities	None
Habitat	Amphibious
Intelligence	Animal
Uses	Uses nothing
Holiness	Natural
Size	Giant
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 bladed weapon bigger than a short blade risks lopping a head off, which, considering hydras' unique biology, is not what you want. Even a troll's claws are long enough to do the same. Only a weapon branded with flame will cauterize the wound and prevent more heads from growing. “On the other hand, Confucius is made to say to his disciples, ‘I know how birds can fly, how fishes can swim, and how animals can run. But the runner may be snared, the swimmer may be hooked, and the flyer may be shot by the arrow. But there is the dragon. I cannot tell how he mounts on the wind through the clouds, and rises to heaven. Today I have seen Lao-tsze, and can only compare him to the dragon.’” -Life of Confucius “This Dragon had Two furious Wings Each one upon each Shoulder; With a Sting in his Tail as long as a Flail, Which made him bolder and bolder. He had long Claws, and in his Jaws Four and forty Teeth of Iron; With a Hide as tough, as any Buff, Which did him round environ.” -“An Excellent Ballad of a most dreadful Combat, fought between Moore of Moore-Hall, and the Dragon of Wantley”, retold by Ambrose Philips, _A Collection of Old Ballads. Corrected from the Best and Most Ancient Copies Extant. With Introductions Historical, Critical, Or Humorous_. 1723.

Useful Info

Hydras are notoriously dangerous melee monsters found most often in the Lair and the Swamp. They begin life with 4-8 heads, with each head giving an extra attack. HD, XP, and willpower are not affected by head count. While hydras cannot fly, they can swim quickly through water.

If a melee attack considered "Slashing" does at least 4 damage, it will cut off the hydra's head. Usually, slashing a head off will cause the hydra to heal and grow two more (a net gain of 1 head). The following weapons will cut off hydra heads: Axes, Long Blades, 2-handed Polearms, lajatangs, and Unarmed Combat with the Claws 3 mutation. All other weapons and all other forms of damage will not cut hydra heads. However, if a slashing weapon has the flaming brand, then the hydra's head will be cauterized; this prevents the regrowth / healing (resulting in a net loss of 1 head).

A hydra can have a maximum of 20 heads. A hydra will die instantly if its last head is cut off. If a hydra dies this way, its corpse and any derived undead will have 1 head. Zombie, skeleton, and simulacra hydras will not regrow heads, even if a slashing weapon does not have flaming. A spectral hydra cannot have its heads cut off.

If a hydra kills an enemy, its remaining heads can attack other targets within reach.

While exploring the bottom floor of the Swamp, beware the Lernaean hydra -- this unique hydra has 27 heads and is much more lethal than normal.

Strategy

Hydras are 100% speed, melee only animals that can't open doors or see invisible, though they do swim quickly. Unless the hydra's camping a branch entrance, there's water around, or you move slower than average, you can simply retreat, and enter from a different stair.

Even if you are skilled with a flaming edged weapon, hydras are strong combatants. An adventurer first venturing into Lair is unlikely to win a fair fight. Remember that you don't have to kill everything in Crawl! You can go down a different staircase, escape with a scroll of teleport, or take a detour to another branch.

Tips & Tricks

• Hydras max out at 20 heads, at which point they get 20 individual melee attacks per turn. Don't let this happen.
• They have poison resistance, so poison, curare, and Mephitic Cloud won't work.
• Hydras are cold-blooded, so cold damage (either from a weapon of freezing or Ice Magic) has a chance to slow them down. Edged freezing weapons are not recommended, however, as heads will still grow back.
• Spellcasters tend to have an easier time. Hydras have 0 AC and minimal EV, meaning that a few solid ranged attacks are likely to kill it. These characters will have trouble if the hydra gets into melee range, though. To avoid this, use the Blink spell, an escape item, or run away.

Most level 3+ Conjurations can kill a hydra in 3-6 hits. Summoners can use Summon Blazeheart Golem to explode. Hexers will have a tougher time, due to the hydra's above-average willpower, but a scroll of vulnerability can work.

Alternatives to Edged Weapons

Flaming edged weapons permanently weaken hydras and deal extra damage. But you might not have a flaming weapon you're skilled with, or maybe you're a weaponless Troll. In that case, there are some other options:

• Use a non-edged weapon of the same skill. Polearms have tridents and demon tridents; lajatang users can use a quarterstaff. Unless you have great stats, make sure you're skilled in the weapon. Cross-trained blunt weapons aren't ideal, but may work.
• A potion of lignification gives great AC and Unarmed damage, without cutting heads - perfect for Trolls. Other species can enter Tree Form in a pinch.
• Even characters with only slashing weapons can use certain Invocations:
  • Makhleb: Greater Servants or multiple lesser servants can easily kill hydras.
  • Beogh: Smite works, but incurs a heavy piety cost.
  • Elyvilon: Hydras are natural beasts and can be pacified easily.
  • Lugonu: With high Invocations, you may be able to banish hydras to the Abyss.
  • Qazlal: Blasting hydras with Upheaval works, though it chews through piety.
  • Trog: Summoning one or two ogres to pound them to a pulp is viable. High HD trolls can usually win a fight, even though they cut hydra heads.
• Failing that, ranged weaponry can work well. Other than launchers, the following are easily accessible:
  • Attack wands: Even at low Evocations, a wand of iceblast or wand of acid can usually kill a hydra in 2-5 hits. This is a safe course of action for most characters.
  • Throwing: Javelins are strong, but even boomerangs with some Throwing skill can deal good damage. Trolls and Ogres have access to large rocks, which are incredibly powerful, but their high delay makes them risky to use up close. Okawaru buffs and boomerangs are enough to take out a hydra.
• A tin of tremorstones works well with some Evocations training, due to a hydra's low AC. A phantom mirror uses a hydra's high damage against it, though is not reliable (the original hydra can win the fight).

The following methods do not work:

• Polymorph: Hydras have high HD, and often turn into even tougher monsters. Storm dragons are a particularly common result.
• Low-skill Ranged Weapons: Hydras regenerate quickly; any method which relies on whittling down its HP over time 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 Swamp: Hydras' speed advantage in water will mean you probably cannot outrun them.

Undead Hydras

Hydra corpses that are raised as zombies, skeletons, or simulacra will have the same number of heads as the corpse. Zero-headed corpses will be raised with one head. In any case, you can slice their heads off, but they will never grow back regardless of brand. Note that hydra simulacra can have horrifyingly high damage output if you lack cold resistance (+13-38 cold damage per head). Spectral hydras 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. Beware of the 27-headed hydra zombie!

History

• Prior to 0.31, Blade Hands chopped hydra heads.
• Prior to 0.25, the now-obsolete wand of scattershot was particularly effective in killing them, as hydras have 0 AC.
• Prior to 0.20, the Captain's Cutlass dealt slicing damage and chopped hydra heads.
• Prior to 0.19, vorpal weapons that did 1-3 damage (instead of >=4 like usual) would chop hydra heads.
• Prior to 0.16, short swords and rapiers dealt slashing damage and could remove heads.
• Prior to 0.12, hydras were not cold-blooded creatures, except the Lernaean hydra.

See also

• Hydra Form