Go to Part 1

Yesterday I rolled out some experimental rules for revising hydras and creating new hydroid creatures. Today we’re going to put them into practice with a few sample creatures.

Bear in mind that this is still an installment of an Untested column: The general rules for hydroids haven’t been tested and these specific monsters even less so. If you do find occasion to use them in your own games, please circle back and let us know how it went!

HYDRALING

Baby hydras — also known as hydralings – are two-headed serpents, only developing the legs of an adult hydra during adolescence. The mothers of hydralings have been seen to deliberately bite off one of the heads from their offspring, prompting the growth of an additional head. Some have hypothesized that this is because hydralings never truly sleep (since one of their heads is always awake), but it’s more likely an instinctual action which prompts (or is prompted by) the hydraling’s development.

HYDRALING
Medium monstrosity, unaligned

Armor Class 13 (Natural Armor)
Hit Points Special
Speed 40 ft., swim 20 ft.

STR 12 (+1)
DEX 15 (+2)
CON 12 (+1)
INT 2 (-4)
WIS 10 (+0)
CHA 6 (-2)

Skills Perception +3, Stealth +4
Senses passive Perception 13
Challenge 1/2 (100 XP)

Amphibious. A hydraling can breathe air and water.

Hydroid. The hydraling has two heads. For every 10 points of damage the hydra suffers, one of its heads dies. If all of its heads die, the hydraling dies.

At the end of its turn, the hydraling grows two heads for each of its severed heads, unless it has taken fire damage since the head was severed. A hydraling can have a maximum of five heads.

Multiple Heads. While the hydraling has more than one head, it has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

For each additional head beyond one, it gets an extra reaction that can be used only for opportunity attacks.

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

ACTIONS

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

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: (1d4 +2) piercing damage.

TENTACULAR ABOMINATION

A dog-size creature with eel-like skin. It has no head, but its back is a writhing mass of tentacles.

TENTACULAR ABOMINATION
Medium monstrosity, unaligned

Armor Class 15 (Natural Armor)
Hit Points: Special
Speed 30 ft.

STR 17 (+3)
DEX 12 (+1)
CON 14 (+2)
INT 6 (-2)
WIS 13 (+1)
CHA 6 (-2)

Skills Perception +5
Senses Blindsight 60 ft., passive Perception 15
Challenge 3 (700 XP)

Pack Tactics. The tentacular abomination has advantage on an attack roll against a creature if at least one of the tentacular abomination’s allies is within 5 ft. of the creature and the ally isn’t incapacitated.

Hydroid. The tentacular abomination has five tentacles. For every 10 points of damage the abomination suffers, one of its tentacles dies. If all of its tentacles die, the abomination dies.

At the end of its turn, the abomination grows two tentacles for each of its severed tentacles, unless it has taken acid damage since the head was severed.

Multiple Heads. While the tentacular abomination has more than one head, it has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

For each additional head beyond one, it gets an extra reaction that can be used only for opportunity attacks.

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

ACTIONS

Multiattack. The abomination makes as many tentacle attacks as it has tentacles.

Tentacle. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: (1d6+3) bludgeoning damage. The target is grappled (escape DC 13) by one of the abomination’s tentacles. Until this grapple ends, the tentacular horror can’t use that tentacle on another target.

LENGLIAN SERAPHIM

Wings. Dozens of wings clustered together as if shielding a central mass (although no such mass exists within the impossible dimensional toroid of the Lenglian seraph), with eyes opening and shutting between the wings. Some Lenglian seraphs are also known to emit smoke or aurora-like, multi-colored halos as their wings continue to fold and unfold, stretching, reaching, searching, beating the air around them.

(It is also not unusual for Lenglian seraphs to be confused for a swarm of winged creatures, particularly from a distance.)

LENGLIAN SERAPHIM
Large celestial, lawful good

Armor Class 17 (Natural Armor)
Hit Points Special
Speed fly 80 ft.

STR 22 (+6)
DEX 21 (+5)
CON 14 (+2)
INT 21 (+5)
WIS 16 (+3)
CHA 19 (+4)

Saving Throws Wis +7
Skills Perception +7
Damage Resistance Radiant; Bludgeoning, Piercing, and Slashing from Nonmagical Attacks
Condition Immunities Charmed, Exhaustion, Frightened
Senses Truesight 120 ft., passive Perception 17
Languages All, Telepathy 120 ft.
Challenge 12 (8,400 XP)

Innate Spellcasting. The seraph’s spellcasting ability is Charsima (spell save DC 17). The seraph can innately cast the following spells, requiring only verbal components:

• At will: bless, detect evil and good
• 1/day each: augury, commune

Hydroid. A Lengling seraph has thirty-five wings. For every 5 points of damage the seraph suffers, one of its wings is severed. If all of its wings are severed, the seraph dies.

At the end of its turn, the seraph grows two wings for each of its severed wings, unless it has been splashed with unholy water since the wing was severed or is under the effects of a bane spell.

Many Eyed. A seraph has eyes proportionate to its wings. While the seraph has more than one wing, it has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

For every five wings the seraph has, it gets an extra reaction that can only be used for opportunity attacks.

ACTIONS

Multiattack. The seraphim can make one wing attack for every five wings it has.

Wing. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: (1d8+6) bludgeoning damage.

Radiant Gaze (Recharge 5-6). One creature that the seraph can see within 60 feet of it must make a DC 17 Constitution saving throw, taking 70 (20d6) radiant damage on a failed save, or half as much damage on a successful one.

LEGENDARY ACTION

Can take one legendary action. Only one legendary action can be used at a time, and only at the end of another creature’s turn. Spent legendary actions are regained at the start of each turn.

Buffeting Wings. The seraph beats its wings. Each creature within 10 ft. of the seraph must succeed on a DC 17 Dexterity saving throw or take 1d6+6 bludgeoning damage and be knocked prone. The seraph can then fly up to half its flying speed.

I woke up this morning with a cool idea for how to handle hydras in D&D. A quick check of the 5^th Edition Monster Manual, however, alerted me to the fact that 5^th Edition basically already did it that way.

Well played, 5^th Edition.

Upon further investigation, it became clear that my subconscious had dredged up a goulash of 3^rd Edition, 2^nd Edition, and OD&D mechanics and then regurgitated them.

Which, upon further consideration is a pretty good summary of the design methodology of 5^th Edition. (This is not a critique.)

Hydras, in D&D 5^th Edition, work like this:

Multiple Heads. The hydra has five 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 25 or more damage in a single turn, one of its heads dies. If all of 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 10 hit points for each head regrown in this way.

The heads give a couple other advantages (extra opportunity attacks, it can sleep while still having one head awake to keep watch), but that’s the fundamental mechanic that models the classic hydra.

There are a couple of changes to this approach that I’d like to experiment with:

1. Eliminate the concept of “total hit points” entirely. You can’t kill a hydra unless you chop off all of its heads.
2. Tweak the mechanic so that you can eliminate more than one head per turn.

So if a fighter gets in there and deals 50 points of damage, his flurrying blades will have hacked off a couple of heads at once. Then maybe the rogue leaps onto its back, deals another 25 points of damage, and hacks off a third head. On the hydra’s turn, it will grow back six heads (two for each severed head).

REVISING THE HYDRA

Thus we can say that a hydra should be mechanically defined as:

• # of heads
• A damage threshold at which it loses a head
• At the end of its next turn or after X rounds it can regrow two heads if it has a severed head
• A sealing condition (usually a type of damage) that prevents
• Dies when it runs out heads.

The “Hit Points” entry of their stat block would be listed as “Special”: They only die if they run out of heads.

Here’s what our revised hydra special abilities would look like:

Hydroid. The hydra has five heads. For every 25 points of damage the hydra suffers, one of its heads dies. If all of its heads die, the hydra dies.

At the end of its turn, the hydra grows two heads for each of its severed heads, unless it has taken fire damage since the head was severed.

Multiple Heads. While the hydra has more than one head, it has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

For each additional head beyond one, it gets an extra reaction that can be used only for opportunity attacks.

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

CREATING HYDROID CREATURES

These mechanics can be used as the basis for other hydroid creatures. Here are some proposed guidelines for doing so.

Damage Threshold. This is the number of hit points required to chop off one of the hydroid appendages. These numbers are loosely based around the idea that a character of the appropriate level should be roughly capable of taking out one head per turn.

I’d recommend halving this value if the sealing damage type or other condition is an unusual one. (This would mean that the killing the monster would typically require killing the heads faster than they can grow back.)

# of Heads. Using the Creating Quick Monster Stats table on p. 274 of the Dungeon Master’s Guide, multiply the minimum hit points for your selected CR by 0.75 and then divide by the damage threshold listed above for its CR.

For example, a CR 10 creature would have 206 hp using the table above, so multiply by 0.75 (154) and then divide by 25 (per the damage threshold table above) to determine that your monster should have six heads.

(This is based strictly on reverse-engineering the existing hydra stat block and it’s unclear if it holds up in practice. It seems to pretty reliably give you 4-8 heads, so you could also probably just get away with slotting in 5-6 heads and not worrying about it.)

You can also use this method to very quickly adapt existing stat blocks. For example, if you wanted to have a hydroid warg (CR ½) you’d take the warg’s current hit point total of 26, multiple by 0.75 (19.5), and then divide by 10. The hydroid warg would start with two heads.

Variant: Maximum Number of Heads. In 2^nd Edition, Lernaen hydras could grow maximum of 12 heads. In 3^rd Edition, they were limited to no more than twice its original number of heads. You might consider doing the same for some hydroid creatures.

DESIGN NOTES

Hydras have a well-known gimmick: They regrow their heads unless you cauterize the stumps with fire. It’s a fun gimmick the can create an encounter which mechanically feels different from other encounters. The only problem is that, because the hydra still has a hit points that’s easier to wipe out than its heads, the mechanical gimmick is irrelevant: There’s often little or no advantage to pursuing it, so parties will just bypass it.

This is boring.

So we fix it by eliminating the bypass. Just like you can’t bypass a troll’s regeneration by just dealing lots of hit point damage to it, you can’t bypass a hydra’s heads.

And, just as regeneration mechanics were created for trolls and now underlie a whole bunch of creatures, these hydroid mechanics can also be used for all kinds of things. We’ll take a look at several examples of this tomorrow.

Go to Part 2

The much delayed Welcome to the Island, a collection of four scenarios for Over the Edge, will be releasing later this month. If you’re looking for scenarios that embody the design principles I talk about here on the Alexandrian, then this is the book you’ve been waiting for. Jonathan Tweet and I have collaborated on a scenario built around the party-planning game structure. The rest of the team, many of whom I originally recruited for Infinity, have created some really fantastic adventures featuring revelation lists, node-based scenario design, and a lot more cool stuff.

Welcome to the Island also features a small selection of what I now refer to as “scenario tools.” I first started developing these back around 2000 or 2001, early in my freelancing career, and have been slowly refining and adding to them ever since. If you’re just prepping notes for your home campaign, these are not things that you’d need (or want) to include. But published scenarios, they help bridge the gap between the author’s imagination and your gaming table. This often takes the form of giving you the tools to integrate a published scenario into your campaign: As writers there’s nothing we can do to avoid making a published adventure generic, but we can make it easier for you to take our generic plug-‘n-play module and make it a seamless part of what you and your players are creating.

These tools usually appear in sidebars. This intentionally segregates them from the main text of the scenario so that they don’t muddy up the presentation of the essential information you need at the table.

GROUNDWORK

Groundwork sidebars are used in scenarios to give examples of how a GM can incorporate elements of the scenario into their campaign prior to running the scenario. The idea is that you can make the scenario feel like an organic part of your campaign by properly laying the Groundwork for it.

We tend not to include anything that’s blatantly obvious. For example, you don’t need us to say something like, “This adventure features NPCs. You could have one of them show up before the adventure begins!” (Unless we have a particularly clever or relevant example of how that might work.)

SCENARIO THREADS

Scenario threads are the mirror image of Groundwork sidebars, suggesting ways in which elements of the scenario could be revisited in later scenarios.

In your home campaign, of course, this is something you should be doing organically: Pay attention to the people or places that particularly resonated with your players. If something interests them or is clicking for them, finding ways to reincorporate it into the campaign is an almost guaranteed success.

PLAYTEST TIP

By the time you’ve finished running a scenario, you’ll often have learned a lot about how you could have used it better. Some of these lessons can be applied in future scenarios, but it’s rare for a GM to have an opportunity to run the same scenario a second time. In published scenarios, though, we have the opportunity to share the insights we’ve gained during out playtests. These Playtest Tips are the “best practices” and offer suggestions for how particular encounters can be handled, alert you to potential problem areas, and try to provide other insights gleaned from our playtesting.

INTERSECTION

This is the newest addition my scenario toolkit and one that I picked up from previous editions of Over the Edge. Intersections reference other published scenarios and suggest how the material in that scenario could be tied to the material in this one. (For example, there’s a strange paranormal gadget in one scenario and a mad scientist in another scenario. When describing the mad scientist’s laboratory, we might include an Intersection that points out you could include a prototype or design notes for the paranormal gadget here, suggesting that this mad scientist was the one who developed it in the first place.)

For Welcome to the Island, these Intersections are limited to other scenarios in the same book. But future anthologies can include references between books, too.

FINAL THOUGHTS

The description of scenario tools in Welcome to the Island also includes revelation lists, which have been discussed here on the Alexandrian as part of the Three Clue Rule. I’d have included adversary rosters, too, but they aren’t used for any of the scenarios in this book. This material, along with the other tools described above, will be repeated in future adventure anthologies for Over the Edge because they weren’t included in the core rulebook. You can contrast this approach with Infinity, where I made sure these tools were described in the core rulebook specifically so that I wouldn’t have to explain them in every adventure we wanted to use them in.

(Which would be all of them, because they’re useful tools.)

I encourage other authors and publishers to also make use of these tools when writing scenarios for publication. They’re incredibly useful and I don’t feel like they should be put in a lockbox.

And if you have any suggestions for other useful tools I could be including in my published scenarios that would make them more useful for you to use at home, please let me know!