Hydra

Type	Hydra	Fire-breathing Hydra	Lernaean Hydra
Species	beast
No. Appearing	1	1	1
Behaviour	solitary
Range	jungle, subterranean	ruin
Size	10 ft. tall	10 ft. tall	10 ft. tall
Weight	600-1,400 lbs.	720-960 lbs.	1080 lbs.
Intelligence	4	4	4
Armour Class	5	5	5
Hit Dice	5-12	6-8	9
Action Points	body, 3 AP; heads 1 AP each
Max. Stride	2	2	2
THAC0	14-18	16-17	15
Hp/Die	d10, d4+d6 or d12	d10 or d4+d6	d4+d6
Attack Form	5-12: (bite)	6-8: (bite)	9: (bite)
Damage	bite (2-12)
Special Attack	venom	breath weapon, venom	immortal head, regeneration venom

Hydrae are huge, serpentine monstrosities that dwell within partially or completely submerged subterranean or dilapidated lairs. These creatures are the progeny of Typhon and Echidna, their numbers exceeding one hundred or so, spanning across regions from the Mediterranean to the Middle East and as far as southern India.

The hydra possesses a massive, corpulent body, with its rear portion measuring approximately 10 feet in width and 14 feet in length, terminating in a stubby tail. At the front of this muscular, leathery bulk, it's supported by two colossal stalk-like legs. Sprouting forth from the forepart of this sinewy mass are numerous snake-like tentacles, each adorned with ridged or knobbed heads, bearing a striking resemblance to dragons, with which the creature is said to share a distant kinship.

The hydra's heads are remarkably agile and possess a striking range of up to 15 feet outward when they launch their attacks (3 hexes. The creature is capable of assaulting opponents from all directions simultaneously. If it wishes, the hydra can attack with up to four of its heads upon a single foe. To safeguard themselves, hydrae prefer to confront adversaries in sufficiently deep water, allowing them to submerge if they're pressed in the attack. This also means that enemies must wade into waist-deep water to engage them in melee. The odds of encountering a hydra outside of a watery habitat are quite low, occurring only once in every ten instances.

The fire-breathing hydra dwell in hot-water caves, where visible steam rises from the water surface. The temperature is usually that of a hot bath.

Hit Points

The unique anatomy of the hydra presents an intriguing challenge for would-be adversaries. It's hit points are concentrated in its body, so that the individual heads can be hit and sustain damage, or even destroyed, without this directly affecting the hydra's overall health.

Therefore the hydra employs a defensive strategy by positioning its heads as a protective barrier between itself and potential threats, making it challenging to harm or ultimately slay. It has an instinctual awareness of the danger posed to its vulnerable body, and any creature attempting to approach the body is attacked aggressively.

When it comes to attacks on its heads, the hydra possesses remarkable resilience. Damage of less than 8 hit points inflicted upon a head is shrugged off and disregarded by the creature. However, if a single blow with an edged weapon, delivers 9 or more damage to a head, that head is severed from the hydra's body. As heads are severed, the creature's body becomes increasingly exposed, enabling direct attacks.

Combatants have the option to employ ranged weapons and spells to target the hydra's body, but this is precisely why the hydra maintains its body submerged in water as a defensive measure. When a hydra loses approximately half of its original heads, if it has the opportunity, the creature will submerge and retreat, seeking a location where it can recuperate and regrow its lost heads. Each head requires between 6 and 8 weeks to grow. Pursuing the hydra would require engaging it in its lair, which is typically submerged underwater, posing even greater challenges for those seeking to defeat the creature.

Advantages

Venom. Hydras possess a moderate toxin, which necessitates a saving throw each time one of a heads lands a successful hit. Failing this save results in the victim enduring 2 hit points of damage per round, for the next six rounds. Multiple failed saves can stack up quickly, so that careful attention must be paid to how much venom has been taken and how long the damage lasts for each. All hydras are venomous.

Breath weapon. The fire-breathing hydra produces a jet that's one hex wide and two hexes long from each head; this causes 8 damage (half if saved against). There's a 4 in 10 chance that any given head will breathe in a given round, rather than attacking with a bite. Once it's breathed fire, a head requires three rounds before re-acquiring the ability sufficiently to do it again, during which time the head attacks normally. The carried items of any combatant that has failed save, on the side facing the hydra, must make saving throw against magical fire.

Regeneration: Applying only to the Lernaean hydra, when this beast's heads are cut off, the stump not only regenerates but forms two heads, where before there was only one. After a lapse of two rounds, both heads have fully regrown and their serpentine necks have separated and merged with the rest of the hydra's heads. Upon the third round, both heads can attack normally.

This regenerative process continues until the Lernaean hydra reaches a maximum of 18 heads. However, given the opportunity to retreat, the extra heads will gradually be shed over several weeks, returning the creature's head count to its usual nine.

Because when the head is lopped off, the neck drops prone to the ground, may be possible to apply a burning branch or some other brand to the severed neck. This must be done immediately, in the next combat round after the head was cut off. If done, this prevents the severed neck from forming two new heads. It might also be accomplished using a torch, burning oil or pitch, or magical means. Of course, this strategy is impossible if the hydra is half-submerged in water.

Immortal head: The Lernaean hydra also possesses a single "immortal head," which is impervious to death. When attacking, the immortal head inflicts double the usual damage, amplifying the threat it poses. While it can be severed from the body, this requires an extraordinary amount of damage in a single blow, 23 damage. And even if it's severed, the immortal head does not perish. Instead, it remains functional and capable of swimming, or flipping itself towards an enemy to attack. If able to escape, the immortal head can grown an entirely new hydra from itself. The exact duration of this regeneration is unknown, but it's believed to require many months.

See Bestiary