Hydra

  Five-Headed Hydra Six-Headed Hydra Seven-Headed Hydra
  Huge Magical Beast Huge Magical Beast Huge Magical Beast
Hit Dice: 5d10+28 (55 hp) 6d10+33 (66 hp) 7d10+38 (77 hp)
Initiative: +1 +1 +1
Speed: 20 ft. (4 squares), swim 20 ft. 20 ft. (4 squares), swim 20 ft. 20 ft. (4 squares), swim 20 ft.
Armor Class: 15 (–2 size, +1 Dex, +6 natural), touch 9, flat-footed 14 16 (–2 size, +1 Dex, +7 natural), touch 9, flat-footed 15 17 (–2 size, +1 Dex, +8 natural), touch 9, flat-footed 16
Base Attack/Grapple: +5/+16 +6/+17 +7/+19
Attack: 5 bites +6 melee (1d10+3) 6 bites +8 melee (1d10+3) 7 bites +10 melee (1d10+4)
Full Attack: 5 bites +6 melee (1d10+3) 6 bites +8 melee (1d10+3) 7 bites +10 melee (1d10+4)
Space/Reach: 15 ft./10 ft. 15 ft./10 ft. 15 ft./10 ft.
Special Attacks:
Special Qualities: Darkvision 60 ft., fast healing 15, low-light vision, scent Darkvision 60 ft., fast healing 16, low-light vision, scent Darkvision 60 ft., fast healing 17, low-light vision, scent
Saves: Fort +9, Ref +5, Will +3 Fort +10, Ref +6, Will +4 Fort +10, Ref +6, Will +4
Abilities: Str 17, Dex 12, Con 20, Int 2, Wis 10, Cha 9 Str 17, Dex 12, Con 20, Int 2, Wis 10, Cha 9 Str 19, Dex 12, Con 20, Int 2, Wis 10, Cha 9
Skills: Listen +6, Spot +6, Swim +11 Listen +6, Spot +7, Swim +11 Listen +7, Spot +7, Swim +12
Feats: Combat ReflexesB, Iron Will, Toughness Combat ReflexesB, Iron Will, Toughness, Weapon Focus (bite) Combat ReflexesB , Iron Will, Toughness, Weapon Focus (bite)
Environment: Temperate marshes (Pyro: Warm marshes) (Cryo: Cold marshes) Temperate marshes (Pyro: Warm marshes) (Cryo: Cold marshes) Temperate marshes (Pyro: Warm marshes) (Cryo: Cold marshes)
Organization: Solitary Solitary Solitary
Challenge Rating: 4 (normal); 6 (pyro- or cryo-) 5 (normal); 7 (pyro- or cryo-) 6 (normal); 8 (pyro- or cryo-)
Treasure: 1/10 coins; 50% goods; 50% items 1/10 coins; 50% goods; 50% items 1/10 coins; 50% goods; 50% items
Alignment: Usually neutral Usually neutral Usually neutral
Advancement:
Level Adjustment:

  Eight-Headed Hydra Nine-Headed Hydra Ten-Headed Hydra
  Huge Magical Beast Huge Magical Beast Huge Magical Beast
Hit Dice: 8d10+43 (87 hp) 9d10+48 (97 hp) 10d10+53 (108 hp)
Initiative: +1 +1 +1
Speed: 20 ft. (4 squares), swim 20 ft. 20 ft. (4 squares), swim 20 ft. 20 ft. (4 squares), swim 20 ft.
Armor Class: 18 (–2 size, +1 Dex, +9 natural), touch 9, flat-footed 17 19 (–2 size, +1 Dex, +10 natural), touch 9, flat-footed 18 20 (–2 size, +1 Dex, +11 natural), touch 9, flat-footed 19
Base Attack/Grapple: +8/+20 +9/+22 +10/+23
Attack: 8 bites +11 melee (1d10+4) 9 bites +13 melee (1d10+5) 10 bites +14 melee (1d10+5)
Full Attack: 8 bites +11 melee (1d10+4) 9 bites +13 melee (1d10+5) 10 bites +14 melee (1d10+5)
Space/Reach: 15 ft./10 ft. 15 ft./10 ft. 15 ft./10 ft.
Special Attacks:
Special Qualities: Darkvision 60 ft., fast healing 18, low-light vision, scent Darkvision 60 ft., fast healing 19, low-light vision, scent Darkvision 60 ft., fast healing 20, low-light vision, scent
Saves: Fort +11, Ref +7, Will +4 Fort +11, Ref +7, Will +5 Fort +12, Ref +8, Will +5
Abilities: Str 19, Dex 12, Con 20, Int 2, Wis 10, Cha 9 Str 21, Dex 12, Con 20, Int 2, Wis 10, Cha 9 Str 21, Dex 12, Con 20, Int 2, Wis 10, Cha 9
Skills: Listen +7, Spot +8, Swim +12 Listen +8, Spot +8, Swim +13 Listen +8, Spot +9, Swim +13
Feats: Combat ReflexesB , Iron Will, Toughness, Weapon Focus (bite) Blind-Fight, Combat ReflexesB, Iron Will, Toughness, Weapon Focus (bite) Blind-Fight, Combat ReflexesB, Iron Will, Toughness, Weapon Focus (bite)
Environment: Temperate marshes (Pyro: Warm marshes) (Cryo: Cold marshes) Temperate marshes (Pyro: Warm marshes) (Cryo: Cold marshes) Temperate marshes (Pyro: Warm marshes) (Cryo: Cold marshes)
Organization: Solitary Solitary Solitary
Challenge Rating: 7 (normal); 9 (pyro- or cryo-) 8 (normal); 10 (pyro- or cryo-) 9 (normal); 11 (pyro- or cryo-)
Treasure: 1/10 coins; 50% goods; 50% items 1/10 coins; 50% goods; 50% items 1/10 coins; 50% goods; 50% items
Alignment: Usually neutral Usually neutral Usually neutral
Advancement:
Level Adjustment:

  Eleven-Headed Hydra Twelve-Headed Hydra
  Huge Magical Beast Huge Magical Beast
Hit Dice: 11d10+58 (118 hp) 12d10+63 (129 hp)
Initiative: +1 +1
Speed: 20 ft. (4 squares), swim 20 ft. 20 ft. (4 squares), swim 20 ft.
Armor Class: 21 (–2 size, +1 Dex, +12 natural), touch 9, flat-footed 20 22 (–2 size, +1 Dex, +13 natural), touch 9, flat-footed 21
Base Attack/Grapple: +11/+25 +12/+26
Attack: 11 bites +16 melee (1d10+6) 12 bites +17 melee (2d8+6)
Full Attack: 11 bites +16 melee (1d10+6) 12 bites +17 melee (2d8+6)
Space/Reach: 15 ft./10 ft. 15 ft./10 ft.
Special Attacks:
Special Qualities: Darkvision 60 ft., fast healing 21, low-light vision, scent Darkvision 60 ft., fast healing 22, low-light vision, scent
Saves: Fort +12, Ref +8, Will +5 Fort +13, Ref +9, Will +6
Abilities: Str 23, Dex 12, Con 20, Int 2, Wis 10, Cha 9 Str 23, Dex 12, Con 20, Int 2, Wis 10, Cha 9
Skills: Listen +9, Spot +9, Swim +14 Listen +9, Spot +10, Swim +14
Feats: Blind-Fight, Combat ReflexesB, Iron Will, Toughness, Weapon Focus (bite) Blind-Fight, Combat ReflexesB , Improved Natural Attack (bite), Iron Will, Toughness, Weapon Focus (bite)
Environment: Temperate marshes (Pyro: Warm marshes) (Cryo: Cold marshes) Temperate marshes (Pyro: Warm marshes) (Cryo: Cold marshes)
Organization: Solitary Solitary
Challenge Rating: 10 (normal); 12 (pyro- or cryo-) 11 (normal); 13 (pyro- or cryo-)
Treasure: 1/10 coins; 50% goods; 50% items 1/10 coins; 50% goods; 50% items
Alignment: Usually neutral Usually neutral
Advancement:
Level Adjustment:

Hydras are reptile-like monsters with multiple heads. A hydra is gray-brown to dark brown, with a light yellow or tan underbelly. The eyes are amber and the teeth are yellow-white. It is about 20 feet long and weighs about 4,000 pounds. Hydras do not speak.

Combat

Hydras can attack with all their heads at no penalty, even if they move or charge during the round.

A hydra can be killed either by severing all its heads or by slaying its body. To sever a head, an opponent must make a successful sunder attempt with a slashing weapon. (The player should declare where the attack is aimed before making the attack roll.) Making a sunder attempt provokes an attack of opportunity unless the foe has the Improved Sunder feat. An opponent can strike at a hydra’s heads from any position in which he could strike at the hydra itself, because the hydra’s head writhe and whip about in combat. An opponent can ready an action to attempt to sunder a hydra’s head when the creature bites at him. Each of a hydra’s heads has hit points equal to the creature’s full normal hit point total, divided by its original number of heads. Losing a head deals damage to the body equal to half the head’s full normal hit points. A natural reflex seals the neck shut to prevent further blood loss. A hydra can no longer attack with a severed head but takes no other penalties.

Each time a head is severed, two new heads spring from the stump in 1d4 rounds. A hydra can never have more than twice its original number of heads at any one time, and any extra heads it gains beyond its original number wither and die within a day. To prevent a severed head from growing back into two heads, at least 5 points of fire or acid damage must be dealt to the stump (a touch attack to hit) before the new heads appear. A flaming weapon (or similar effect) deals its energy damage to the stump in the same blow in which a head is severed. Fire or acid damage from an area effect may burn multiple stumps in addition to dealing damage to the hydra’s body. A hydra does not die from losing its heads until all its heads have been cut off and the stumps seared by fire or acid.

A hydra’s body can be slain just like any other creature’s, but hydras possess fast healing (see below) and are difficult to defeat in this fashion. Any attack that is not (or cannot be) an attempt to sunder a head affects the body.

Targeted magical effects cannot sever a hydra’s heads (and thus must be directed at the body) unless they deal slashing damage and could be used to make sunder attempts.

Fast Healing (Ex): Each round, a hydra heals damage equal to 10 + the number of its original heads.

Skills: Hydras have a +2 racial bonus on Listen and Spot checks, thanks to their multiple heads.

A hydra 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.

Feats: A hydra’s Combat Reflexes feat allows it to use all its heads for attacks of opportunity.