Welcome to Homebrew Horrors, a series where you get a set of brand-new homebrew monsters, plus lore and worldbuilding details that you can use to plant them in your own D&D setting. This week, check out three monstrous new hydras: the arctic cryohydra, the magma-born pyrohydra, and the vegetal floralhydra. Each threatens to bring the hurt to your players in new and exciting ways, and they’re the perfect way to throw your players who have memorized the Monster Manual for a loop!
Cryohydra
The cryohydra is a horrific, blubbery mammal not unlike a massive whale with four muscular tentacles and multiple heads on long, serpentine necks. Its heads, once severed, leave behind stumps which regrow two new heads in their place unless cauterized by flames. Even though it is a creature of flesh and blood, the supernatural frost that birthed it suffuses its entire body.
Created by the divine power of Auril the Frostmaiden, cryohydras are monstrous, many-headed amphibians untroubled by temperatures as low as –100 degrees Fahrenheit. Cryohydras stalk icy wastes and dwell in frigid pools, typically subsiding on arctic fish but devouring any mortal foolish enough to wander too close to their lairs. Some cryohydras swim through arctic seas, pursuing prey as large as killer whales—or even the whaling ships that hunt them.
A cryohydra typically makes its lair in aboveground ice caves, abandoned temples to the goddess that created it, or partially submerged sea caves. When creating a cryohydra lair, consider using the Healing Pools map or Coastal Temple map from Mythic Odysseys of Theros as a starting point.
If you’re playing in another campaign setting, you can decide upon a different deity of ice, winter, and snow to have created a cryohydra. In Eberron, this deity could be the Devourer, one of the Dark Six and the divine embodiment of nature’s wrath. The Devourer’s cryohydras are sleek, icy blue, and lined with white fins to help them swim through arctic oceans. In Wildemount, this deity could be the Raven Queen, whose hydras are bone-white, yet covered in patches of long, black feathers. In Theros, cryohydras are nonetheless servants of Nylea, whose power over nature can appear chaotic and unpredictable to mortals ill-versed in her divine modes of thought.
The cryohydra is a fearsome CR 10 monster. See its full statistics and add this monster to your game using the D&D Monster Homebrew tool!
Pyrohydra
The pyrohydra is a hulking serpent of pure magma with a dozen flailing heads. Born of divine elemental power, this living pyroclastic floe leaves a trail of oozing, burning destruction wherever it moves. Its heads are amorphous extensions of its own elemental nature. Like other hydras, it can grow more heads whenever one of its existing heads is destroyed—however, it can also channel its own elemental life force into creating new heads. More frightful still, it can destroy its own heads to create an eruption of magma and toxic gas, burying all nearby in molten rock.
Pyrohydras were first brought into being by Imix, fiery prince of Elemental Evil, who used them to guard his domain on the Elemental Plane of Fire. Since their first creation, pyrohydras have become apex predators of the molten, flaming seas of the Plane of Fire—and have occasionally emerged into the Material Plane, sometimes called by Vanifer’s Cult of the Eternal Flame, sometimes emerging through natural planar rifts. On the Material Plane, pyrohydras frequently lair in natural volcanos, but they also makes lairs in ancient forests, and take great joy watching the world around them burn to cinders. When creating a pyrohydra lair, consider using the Volcano Temple map or Forest Shrine map from Mythic Odysseys of Theros, or the Weeping Colossus from Princes of the Apocalypse as a starting point.
These elemental behemoths possess brutish intelligence, and delight in appearing to mortals as demigods and demanding their worship. They have little use for material tribute, for such gifts simply melt in their molten bodies, but living sacrifices entertain them greatly.
The pyrohydra is a gargantuan, CR 13 creature of pure magma. See its full statistics and add this monster to your game using the D&D Monster Homebrew tool!
Floralhydra
The floralhydra is a verdant beast with a body shaped like a hog-sized plant bulb, propped up on a wriggling mess of vine-like legs. Emerging from this slimy, leafy bulb are five thick vines that writhe around like flailing pythons. At the end of each of these vines is a head shaped like a smaller bulb. When this head opens to feed, it unwraps into a pink, five-petaled maw dripping with acid and lined with small white hooks that grab its prey.
Unlike other hydras, which are the progeny of divine beings, floralhydras are the twisted creations of a druidic order called the Circle of Thorns. These zealots believe that plants are the superior form of life, particularly those that have been granted sapience through magic. Floralhydras are their proudest creations, for while they are adept at devouring the circle’s foes, they have another purpose. All beings devoured by a floralhydra are digested into dandelion-like seeds. Once a floralhydra goes to seed, all of the flesh-and-blood creatures it devoured are reborn as sentient, plantlike facsimiles of their former selves.
Floralhydras, while sentient, are about as intelligent as a well-trained dog. They show kindness to their masters and are capable of love and loyalty, but lack reason or any sort of higher thought.
The floralhydra is a CR 5 monster that lives to devour all humanoids! See its full statistics and add this monster to your game using the D&D Monster Homebrew tool!
What kind of homebrew monsters have you made for you game? Learn how to make homebrew horrors of your own in the D&D Monster Homebrew tool with Design Workshop: Monsters!
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James Haeck is the lead writer for D&D Beyond, the co-author of Waterdeep: Dragon Heist, Baldur's Gate: Descent into Avernus, and the Critical Role Explorer's Guide to Wildemount, a member of the Guild Adepts, and a freelance writer for Wizards of the Coast, the D&D Adventurers League, and other RPG companies. He lives in Seattle, Washington with his fiancée Hannah and their animal companions Mei and Marzipan. You can find him wasting time on Twitter at @jamesjhaeck.
Great article, and looking like it will be a great series overall.
My one issue with 5e hydras(homebrew and official) is that if you do enough damage to it, you slay it. The original hydra could get to hundreds of heads and not be hurt, but for the 5e hydra that would require taking 2,500 damage, and it would be way dead. I suppose you could damage it by striking at its body, but I always think of the front of it as being a roiling mass of heads that you almost never see past.
A solution I made when I ran a hydra for a group is I gave the body 72 HP, and said that if you kill that, the hydra is dead. Then, each head had 20 HP, and at the start of its turn, it gained two heads for every one head it had lost(afterwards, I realized that it should have been the end of its turn). Also, you had to hit each stump with fire damage to stop that stump from regenerating.
I also gave it acid breath, but that is just a side note. It wasn't *too* powerful.
They ended up just killing all of the heads before the hydra got a turn, so all my work went to waste. :-(
YES MORE DRUID STUFF
What about a constructed hydra? Maybe as some sort of tribute to Tiamat, with each head breathing a different elemental energy, or poison/acid. Could be powered by the souls of various hydras as a fluff thing.
I like the idea. Why not the souls of the different chromatic dragons? Each heads power could be determined by the age of the dragon sacrificed to power each head. It could be quite a fun end of campaign boss.
These hydras are great! Is there any way to get the monsters from this series to show up in the encounter builder?
My post-Avernus player characters are going up against that pyrohydra. No question. What a brutal adversary!
For sure it's going in Level 15 of Undermountain.
Now to come up with some lair actions...
Good article, but nothing beats the False Hydra.
Really cool spins on the normal hydra, and I agree with what other people are saying here: this should be a permanent series for the next ten years at least! Bit of a shame that we have to subscribe to get these in our homebrew, but you can always just search for it and view it. Circle of Thorns also sounds like a sneak preview of some kind...
Side note: If Circle of Thorns druids are that convinced by the power of plants, surely they must have found a way to work the Floralhydra effect on themselves while retaining their abilities. Maybe that is the ultimate aim, and soon plant-druids will be overrunning the realms!
based
Great article. What about doing variants on the tarrasque? I really want a zombie tarrasque.
I think these are some pretty good hydras. Nice elemental variants and hydras feel almost criminally underused. I think the Create Heads action on the Pyrohydra in particular is pretty cool since it takes damage by creating heads; it forces the creature to either decide between its health or an obscene damage output.
However, your CR ratings are far too low, by a large margin for some of them. I ran these through a CR calculator and these were what I got:
The Floralhydra is a CR 8, not a CR 5.
The Cryohydra is a CR 21, not a CR 10.
The Pyrohydra is a CR 27, not a CR 13.
Most of these come from the sheer damage output of the hydras. The Cryohydra, with its 7 heads, can deal an average of 119 damage per round. The pyrohydra with its 12 heads can deal an average of 324 damage per round. The pyrohydra in particular is pretty nuts with its damage output.
Otherwise, they're good. Would also like to see a series of this.
Interesting things, especially pyrohydra. Can I recommend some sort of Ideas for fiends who have somehow turned good, like Krikendolt from BGDIA?
Also, as the creation of a god, It seems to me like the cryohydra should be considered a titan, or am I missing some criteria?
that would be cool but also very overpowered.
true, but it does not alwways have that many heads. it should be more like 7, 19, 25
That isn't how CR calculation works though. Calculating damage per round for CR means calculating the average of its highest source of damage output if it can do that attack 3 turns in a row. A hydra can have all of its heads for 3 turns in a row, so it's still calculated. A pyrohydra can potentially end up first in initiative order and deal an average of 300+ damage to the party. A party of four level 20's would have trouble with that much damage.
Granted, you are correct in that hydras are particularly weird when it comes to how difficult they are; the more damage they take, the weaker they can become.
Also important to remember that CR isn't an exact science, but is important if your game uses experience over the milestone system.
I’m a really big fan of this series and I hope that you can continue it in the future.
You can eat the last one and still be considered a Vegan no?
Correct.
Nope. It's sentient and feels pain. I doubt any vegan would be ok eating that.
Source: partner is vegan.