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Greco-Roman Hydra

I am currently running my players through an O5R (D&D 5e hacked to feel and play like OSR) version of Odyssey of the Dragonlords and decided to google up some greek/roman monsters for inspiration and found this (and other) great entries.  I like this version of the hydra.  Here is a 5e version of the creature.


Lernaean Hydra. The Original. Immortal, nearly impossible to kill or survive an encounter. Has telepathic control over all hydrae. Many poison-related attacks and powers.  See further down for this legendary creatures statiscis.

Greater Hydra. Very dangerous. Appropriate for characters level 10+. Greatly resents whoever severed it from the Lernaean Hydra. Often holds many Lesser Hydrae in its control. Use the ironscale hydra as the base creature with the following additional traits:

  • Telepathic. A great hydra can telepathically communicate with intelligent creatures in its presence, regardless of language barriers. It can also command all hydra of a lower category as if the creature was charmed up to a 10-mile radius.
  • Survivor. Every hydra has grown from the severed hydra-head of a larger hydra. Severed hydra heads, no matter the size, are able to grow appendages and escape the attacker. After some time, they transform into the body of a full hydra one category lower than the original hydra.
  • Poison Breath (Recharge 5–6). The hydra uses all its heads to exhale poisonous gas in a 60-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 16d6 poison damage on a failed save, or half as much damage on a successful one. Reduce the damage of this attack by 1d6 for each head lost.
  • Spit Acid. The hydra spits acid in a line that is 30 feet long and 5 feet wide. Each creature in that line must make a DC 14 Dexterity saving throw, taking 4d6 acid damage on a failed save, or half as much damage on a successful one.

Lesser Hydra. Appropriate for characters level 8-10. Cannot remember Lernaean Hydra, which seeks to escape the domination of its progenitor Greater Hydra. Use the standard hydra as the base creature with the following additional traits:

  • Survivor. Every hydra has grown from the severed hydra-head of a larger hydra. Severed hydra heads, no matter the size, are able to grow appendages and escape the attacker. After some time, they transform into the body of a full hydra one category lower than the original hydra.
  • Poison Breath (Recharge 6). The hydra uses all its heads to exhale poisonous gas in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking 12d6 poison damage on a failed save, or half as much damage on a successful one. Reduce the damage of this attack by 1d6 for each head lost.
  • Spit Acid (Recharge 6). The hydra spits acid in a line that is 30 feet long and 5 feet wide. Each creature in that line must make a DC 13 Dexterity saving throw, taking 3d6 acid damage on a failed save, or half as much damage on a successful one.

Small Hydra. Suitable for characters levels 3 and under. About the size of a dog. Lives as a wild animal. Use the standard giant poisonous snake as the base creature with the following additional traits:

  • Change the creatures type to monstrosity.
  • It is immune to the poisoned condition and poison damage.
  • Survivor. Every hydra has grown from the severed hydra-head of a larger hydra. Severed hydra heads, no matter the size, are able to grow appendages and escape the attacker. After some time, they transform into the body of a full hydra one category lower than the original hydra.
  • Hold Breath. The hydra can hold its breath for 1 hour.
  • Multiple Heads. The hydra has two heads. While it has more than one head, the hydra has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious. Whenever the hydra takes 5 or more damage in a single turn, one of its heads dies. If all its heads die, the hydra dies. At the end of its turn, it grows two heads for each of its heads that died since its last turn, unless it has taken fire damage since its last turn. The hydra regains 5 hit points for each head regrown in this way.
  • Reactive Heads. For each head the hydra has beyond one, it gets an extra reaction that can be used only for opportunity attacks.
  • Wakeful. While the hydra sleeps, at least one of its heads is awake.
  • Multiattack. The hydra has two heads and makes two bite attacks.
  • Poison Breath (1/Day). The hydra combines its heads to exhale poisonous gas in a 15-foot cone. Each creature in that area must make a DC 11 Constitution saving throw, taking 6d6 poison damage on a failed save, or half as much damage on a successful one.
  • Spit Acid (1/day). The hydra spits acid in a line that is 15 feet long and 1 foot wide. Each creature in that line must make a DC 12 Dexterity saving throw, taking 2d6 acid damage on a failed save, or half as much damage on a successful one.

Micro Hydra. A tiny creature with a deadly bite. Captured and used by assassins. Easily crushed. This creature is identical to a poisonous snake, except, if crushed the creature crushing it takes 1d4 acid damage. As a hydra it has the following additional traits:

  • Change the creatures type to monstrosity.
  • It is immune to the poisoned condition and poison damage.
  • Hold Breath. The hydra can hold its breath for 1 hour.

Other ideas:

You can also use the amphisbaena as a step between micro and small. It has the additional traits of a micro hydra. You can also use the polukranos as a step between the greater and Lernaen.


LERNAEAN HYDRA

Gargantuan monstrosity (mythic, unique) , unaligned
Armor Class 21 (natural armor)
Hit Points 594 (22d20 + 154)
Speed 40 ft., swim 40 ft.
STR DEX CON INT WIS CHA
27 (+8) 18 (+4) 25 (+7) 2 (-4) 17 (+3) 8 (-1)
Saving Throws DEX +11, CON +14, WIS +10, CHA +11
Skills Perception +17, Stealth +11
Damage Immunities Acid, Poison
Condition Immunities Poisoned
Senses Blindsight 60 ft., passive Perception 27
Languages
Challenge 22 (41,000 XP); Proficiency Bonus +7

Aura of Poison. The hydra can activate or deactivate this feature as a bonus action. While active, the aura deals 5 poison damage to any creature that ends its turn within 30 feet of the hydra.

Hold Breath. The hydra can hold its breath for 1 hour.

Hydra Blood. When the hydra takes piercing or slashing damage, each creature within 5 feet of the hydra takes 2d8 acid damage. This acid corrodes all metal items – including magical armour and weapons.  A weapon takes -1 damage each time it is exposed to this acid, if the weapons damage total is reduced to 0, it is permanently destroyed.  Metal armor suffers the same effects taking a cumulative -1 to AC each time it is exposed to hydra blood.  If the armour’s AC drops to 10 it is also destroyed. So long as the weapon or armour is not destroyed, it can be repaired by smith or wizard (as appropriate).

Immortal Multiple Heads. The hydra has 5 + 1d4 heads at any given time. While it has more than one head, the hydra has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, or knocked unconscious. Whenever the hydra takes 65 or more damage in a single turn, one of its heads dies.  At the end of its turn, it grows two heads for each of its heads that died since its last turn, unless it has taken fire damage since its last turn. The hydra regains 10 hit points for each head regrown in this way. The central head is immortal and can not be permanently killed.  It will always regenerate after 1 week starting with 1 head and then adding 1d4 heads each week to a maximum of 9. Its INT score is affected by the number of heads it has, it gains +2 INT for each head it has and, correspondingly, losses that many points of INT each time it loses a head.

Legendary Resistance (3/Day). If the hydra fails a saving throw, it can choose to succeed instead.

Reactive Heads. For each head the hydra has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

Survivor. Every hydra has grown from the severed hydra-head of a larger hydra. Severed hydra heads, no matter the size, are able to grow appendages and escape the attacker. After some time, they transform into the body of a full hydra one category lower than the original hydra.

Telepathic. The hydra can telepathically communicate with intelligent creatures in its presence, regardless of language barriers. It can also command all hydra as if the target creature was charmed (no saving throw). The range of this effect is global.  However, the hydra rarely uses this ability (DM’s discretion).

Wakeful. While the hydra sleeps, at least one of its heads is awake.

Actions

Multiattack. The hydra makes as many bite attacks as it has heads.

Bite. Melee Weapon Attack: +15 to hit, reach 20 ft., one target. Hit: 2d10 + 8 piercing damage plus 10 poison damage.

Constrict. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 2d8 + 8 bludgeoning damage and the target is grappled (escape DC 22). Until this grapple ends, the creature is restrained, and the hydra can’t constrict another target. At the start of its turn, the grappled creature automatically takes 2d8 + 8 bludgeoning damage.

Hydra Poison Breath (Recharge 6). The hydra combines its heads and exhales poisonous gas in a 90­-foot cone. Each creature in that area must make a DC 22 Constitution saving throw, taking 22d6 poison damage on a failed save, or half as much damage on a successful one. For each head lost the damage is reduced by 2d6. For each active head the recharge rate of this attack has +1. A creature exposed to this attack automatically has its resistance to poison reduced by 1 level – immunity becomes resistance, resistance becomes normal and normal becomes vulnerable.

Legendary Actions

The hydra can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The hydra regains spent legendary actions at the start of its turn.

  • Move.The hydra moves up to its speed without provoking opportunity attacks.
  • Constrict Attack. The hydra makes a constrict attack.
  • Precognition (Costs 2 Actions). The hydra gets a brief glimpse of the immediate future, gaining advantage on attack rolls and Dexterity-based saving throws until the end of her next turn.

Lair Actions

On initiative count 20 (losing initiative ties), the hydra randomly takes a lair action to cause one of the following effects; the hydra can’t use the same effect two rounds in a row:

  1. Grasping roots and vines erupt in a 20-foot radius centred on a point on the ground that the hydra can see within 120 feet of it. That area becomes difficult terrain, and each creature there must succeed on a DC 15 Strength saving throw or be restrained by the roots and vines. A creature can be freed if it or another creature takes an action to make a DC 15 Strength check and succeeds. The roots and vines wilt away when the hydra uses this lair action again or when the hydra dies.
  2. Pools of water that the hydra can see within 120 feet of it surge outward in a grasping tide. Any creature on the ground within 20 feet of such a pool must succeed on a DC 15 Strength saving throw or be pulled up to 20 feet into the water and knocked prone.
  3. A cloud of swarming insects fills a 20-foot-radius sphere centred on a point the hydra chooses within 120 feet of it. The cloud spreads around corners and remains until the hydra dismisses it as an action, uses this lair action again, or is disabled. The cloud is lightly obscured. Any creature in the cloud when it appears must make on a DC 15 Constitution saving throw, taking 3d10 piercing damage on a failed save, or half as much damage on a successful one. A creature that ends its turn in the cloud takes 3d10 piercing damage.
  4. A magical fog spreads from a point the hydra chooses within 60 feet of it, filling a 15-foot-radius sphere until the hydra dismisses it as an action, uses this lair action again, or is disabled. The fog spreads around corners. Any creature, except the dragon, becomes vulnerable to poison and acid damage while in the area of the fog. 

Regional Effects

The region containing the legendary hydra’s lair is warped by the hydra’s presence, which creates one or more of the following effects:

  • The land within 12 miles of the lair takes twice as long as normal to traverse since the plants grow thick and twisted, and the swamps are thick with reeking mud.
  • Water sources within 1 mile of the lair are supernaturally fouled. Enemies of the hydra that drink such water regurgitate it within minutes.
  • Fog lightly obscures the land within 6 miles of the lair. Within 1 mile this fog is toxic and imposes the poisoned condition on any breathing creature that remains in the area. This condition is removed as soon as the target leaves the area.

 

Posted in 5e, Clash of the Titans, Dungeons & Dragons, Monstrous Compendium, OSR 5e

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