HD 8 AC chain Attacks (1 per head)
Move 12 Int 5 Mor 7
Regenerates 1 body HP per round
Hydradas are just hydras from the Elemental Plane of Hydras. They are hydras with the hydra-ness turned up to 11. They usually begin with 3 heads (2 HD each, but AC as plate, because of how quickly they whip around.) Slashing weapons can sever heads or damage the body; other types of damage can only damage the body. Head damage is mirrored onto the body.
Each of their bites does 1d6 damage. If an attack does 5 or 6 damage, the target must save or a hydra head will grow from their wound on the next turn. The head has a 10' reach, and attacks as a normal hydra would attack, with the same damage and AC. It can be severed normally (but will regrow into two heads unless the stump is cauterized with fire or acid). The host gets -2 to attack a hydra head growing out of their own body. The hydra head preferentially attacks its host (biting them on the face and ears, usually). If the hydra head reduces its own host to 0 HP, it decapitates the host. If the host is decapitated and the hydra-head-sprouting-from-the-wound remains, two hydra heads erupt from the stump on the next turn.
Whenever hydrada blood is spilled there is a d% chance (equal to the damage taken) that a hydra head will sprout from whatever surface the blood spills on. This head has a 20' reach and follows all the normal hydra rules.
Severed heads become 1 HD hydroids after 1 turn. They have no neck, and can be killed like any other little critter. However, unless they take fire or acid damage, they will regenerate to 1 HP
Whoever kills the hydra is afflicted by the hydra's death curse: all creatures will appear to be hydras for the rest of the day. All speech sounds like hissing. All written text appears as "hydra hydra hydra" etc. No save.
HD 1-20 AC chain Attacks (1 per head)
Move 12 Int 5 Mor 7
A zoo hydra is created whenever some really weird shit happens at the zoo. The heads will regrow in 1 round unless salt or urine is applied to the stump. It has one head for every HD.
Heads [d20, or just go down the list]
1. Crocodile - Bite 1d10, but with a -2 to hit.
2. Fox - Bite 1d4. Every 2 turns, reroll a d20 that someone else rolls.
3. Lion - Bite 1d8.
4. Howler Monkey - Howls. Every turn, has a 10% chance of attracting a new random encounter.
5. Giraffe - Smashes for 1d6. Ridiculous 30' reach.
6. Wolf Skull With Glowing Red Eyes - Bites for 1d6. Can reanimate dead things as loyal zombies, 1/turn.
7. Komodo Dragon - Bites for 1d6 + disease.
8. Emu - Pecks for 1d4. Easy to sever: neck only has 1 HP.
9. Bird of Paradise (the flower) - Can cast cure light wounds at will.
10. Ibis - Peck 1d4. Save or lose an eye.
11. Gorilla Hand - Attempts to steal your weapon and hit you with it. Str 16, Dex 12.
12. Rhino - Gores for 1d10 damage. On a miss, there is a 2-in-6 chance that the rhino horn gets stuck in something, trapping the rhino head there for 1 turn.
13. Elephant - Gores for 1d12. Never forgets. (Attacks whoever attacks it first, and never changes targets.)
14. Shark - Bites for 1d8. If the attack roll is 1-3, it attacks another head instead. If the other head is a carnivore, the two heads will start fighting, only stopping when one head is bitten off. (This causes two heads to grow, as normal.)
15. Sloth - Stays asleep until it takes damage, at which point it wakes up and starts biting for 1d4.
16. Viper - Bite 1 damage, save or take 3d6 more over 3 turns.
17. Penguin - Peck 1d4, Every 3 turns, breath a cone of frozen air, 3d6, 20' cone.
18. Zookeeper - Does nothing except scream about emus and madness, begs to be killed, yells at players to bring salt.
19. Cage - On a hit, traps a player inside. On subsequent turns, beats "head" against ground, dealing 1d6 damage to occupant automatically. Made of solid metal, but the lock can be picked as normal (usually requires one round to climb on it, and another to pick it, retrys allowed).
20. Dolphin - Doesn't want to fight. It will just make stupid dolphin noises all fight. If it is the only head remaining on the body (i.e. it is a dolphydra) it will run away. It's also tamable, if you have fish.
HD 7 AC leather Attacks (see below)
Move 15 Int 3 Mor 7
The central cow head gores for 1d8 damage.
The left pig head bites for 1d6.
The right goat head rams for 1d4, but does 3x damage on a charge.
The goose-headed tail spits goose shit (ranged attack). On a hit, the target is blinded until they spend a turn wiping it away.
When killed, the barnyard chimera splits open and spills out 3d6 featherless, bloody chickens with red eyes and sharp talons. The chicken have HD 1, AC leather, and claw for 1d4.
It runs on horse legs. It can speak, but it is only repeating mindless farming phrases. "How about that weather, huh?" "Well, let's finish up and then have supper." "Aw hell, she's coming out breach."