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Xenoid Creature

A xenoid can be created by modifying an existing creature’s statistics using the following rules. This can be done to modify any living creature that has been corrupted from within by alien forces from beyond the farthest realms. A xenoid creature uses the base creature’s statistics and abilities except as noted here.

Type. The creature’s type changes to aberration. The creature also gains the shapechanger and mythos subtypes.

Armor Class. A xenoid creature gains a bonus to Armor Class equal to its Intelligence modifier.

Special Attacks. Xenoid creatures gain the following special attack:

Traits. A xenoid creature gains darkvision 60 feet and the following abilities:

  • Energy Resistance. Xenoid creatures gain energy resistance to acid and lightning.
  • Spell Resistance. Xenoid creatures gain a modicum of magical resistance, they add +1d4 to their saving throws against magical effects.
  • Unnatural Anatomy. Xenoid creatures have a chance to negate critical hits due to their strange and deceptive anatomy. If a creature scores a critical hit against a xenoid, the xenoid may make a Constitution saving throw with a DC equal to the result of the attack roll, if successful, the critical hit becomes a normal hit.
  • Unnatural Form. Xenoid creatures seem normal at first glance; however, as an action they can reveal their true alien nature in a horrifying transformation. They can also trigger this transformation as a reaction after a creature scores a critical hit against them. Any nonxenoid creature that can see the xenoid creature when it transforms is affected as if the xenoid creature had cast fear on the creature. This affects only creatures with fewer Levels/CR than the xenoid creature. A creature that saves against a xenoid creature’s unnatural form is immune to the unnatural form of all xenoid creatures of the same type for 24 hours. A xenoid creature can remain in its unnatural form for a number of hours equal to its Challenge. While in its unnatural form, a xenoid creature gains an ability listed under “Monster Features” of the “Creating a monster” rules. Roll a d% to determine the ability it gains, any roll above 90 indicates you should roll twice and gain two abilities but subtract 5 from the roll each time this happens (GM’s discretion of course!). At the GM’s option, all xenoid creatures of a particular kind may share the same ability in their unnatural form or abilities could vary by individual. Likewise, most xenoid creatures have one specific ability that they gain when they shift into their unnatural form, but if desired the ability can be randomly determined each time a xenoid creature assumes its unnatural form. Xenoid creatures crave being in their unnatural form and feel constricted and morose if trapped in their natural bodies for long periods. A xenoid creature can remain in its natural body for a maximum number of hours equal to its Constitution score, after which it becomes shaken and has disadvantage on skill and ability checks until it spends at least 1 hour in its unnatural form. Each hour thereafter that it does not transform it must succeed at a Wisdom saving throw (DC 15, +1 per hour after the first) or be compelled to transform into its unnatural form, becoming confused (as the spell) after the transformation.

Weaknesses. While in its unnatural form, a xenoid creature gains the following weakness.

  • Toxic Reality. The thick and orderly physical reality of the Material Plane is painful and disturbing to a xenoid creature in its unnatural form. Each hour it remains in this form it must succeed on a Constitution saving throw (DC 15, +1 for each hour after the first) or take 1d6 points of psychic damage and become exhausted. This psychic damage cannot be healed until the xenoid creature resumes its normal form or reaches an alien environment more suited to its nature.

Ability Scores. A xenoid creature uses the base creature’s ability scores, but it’s Intelligence is at least 3.

Alignment. A xenoid creature’s alignment is shifted one step towards evil, though it retains the lawful or chaotic component of the base creature’s alignment.

Epic Xenoid Creatures

Epic xenoid creatures follow the same rules as ordinary xenoid creatures, but their alienness is far more pronounced and they are imbued with far greater pseudonatural power.

The epic xenoid template can be applied to any creature that already possesses the xenoid creature template and must have a Challenge level of at least 20. This template overlaps and does not replace the xenoid template – they stack.

Hit Points. The creature gains maximum hit points for its hit-dice. This effect is retroactive.

Ability Scores. +4 Str, +2 Dex, +2 Con; Additional traits. Choose or randomly select 1 when the creature first acquires the template. It then may pick another additional option from those below for each Challenge level it has over 20.

  1. Grab. A mythic xenoid creature in its unnatural form can automatically grapple a target whenever it makes an attack with its tentacles.
  2. Pseudonatural Impregnation. A mythic xenoid creature can transform another living creature into a xenoid creature, permanently granting it the xenoid creature template (or the mythic xenoid creature template, if the target creature is already a mythic creature). This process requires 8 hours, during which the target creature must be helpless or willing. The mythic xenoid creature must remain in continuous intimate physical contact with the target throughout the process. At the end of this time, the mythic xenoid creature must sacrifice 1 HD permanently and the target must succeed on a Constitution saving throw (DC 8 + xenoid creature’s proficiency bonus + its Constitution modifier) or become a xenoid (or mythic xenoid) creature permanently. A willing target may, of course, voluntarily choose to fail the saving throw. If the target saves, the mythic xenoid creature can repeat the process, and each subsequent attempt increases the DC by 1.
  3. Rotting Rake. Each time a mythic xenoid creature succeeds on a grapple with its tentacles, it deals 1d3 points of Strength damage per hit to the target. A successful Constitution saving throw (DC 8 + xenoid creature’s proficiency bonus + its Constitution modifier) halves this Constitution damage (minimum of 1).
  4. Tentacle Rake. A mythic xenoid creature in its unnatural form gains an additional tentacle attack.
  5. True Strike. A mythic xenoid creature can use its true strike ability as part of its attack action at will.
  6. Unnatural Form. Non-epic creatures seeing a mythic xenoid creature’s unnatural form are affected by its fear presence whenever they see it, rather than only being affected if they witness its transformation.

In unnatural form, a mythic xenoid creature gains one of the listed abilities, plus one additional ability for every 4 CR/Level it possesses.


The mythos subtype represents creatures with their origins in the Lovecraftian mythos of ancient alien gods from beyond the stars and madness-inducing forays into secrets man was not meant to know. While mythos creatures are often aliens from elsewhere in the physical universe, they can also be creatures from alien dimensions beyond the bounds of time and space as ordinary mortal creatures understand them. Most mythos creatures are covered by the aberration type, though some may be monstrosities, oozes, plants, undead, or rarely other creature types.

Mythos creatures are sometimes infused with extradimensional power far beyond that of similar creatures. Mythos creatures thus may have maximum hit points per HD, and some of the more complex creatures may have save DCs set to a single value to make them easier for GMs to run. This flat value is generally linked to the creature’s AC.

Alien Cysts: A classic feature of alien nests often casts aberrant things from beyond as being somewhat insectoid, creating hives or cysts built out of mucus and resin exuded through their unnatural orifices and accreted into cells and chambers that seal out the air of the living world and trap in a noxious effluent that more closely mimics the atmosphere of the nightmare dimensions they call home. This can be used as a merely descriptive effect to bring home the strangeness of these beings from beyond, but the following templates presuppose that these pseudonatural “xenoid” creatures are actually dependent on these alien environments if they are to operate freely in their unnatural state. Otherwise, they must remain hidden in their fleshy cages as they walk among the fleshy beings of our world.

Cystic Resin: A xenoid creature can express enough alien cystic resin, sometimes called kaor, to coat a 10-foot square area with an inch-thick layer, which hardens to the strength of solid wood in 1 hour. This takes one hour and can be done once per day, and once applied the resin layer lasts 1 year before decaying into crumbling flakes. At the GM’s option, this material can be shaped into any objects that could normally be crafted out of wood or leather. Alternatively, a xenoid creature can exude a more refined resin called kaorak which has the hardness of steel, but it can produce only a 1-foot-square area an inch thick, sufficient to use as the material for a light or one-handed weapon, or with several days of effort to make an item similar in quality to darkwood. Items made of this alien resin can be made masterwork or even into magical items and follow normal crafting rules.

Section 15: Copyright Notice

Mythos Monsters (5E) © 2020, Legendary Games; Authors Michael "solomani" Mifsud, Robert J. Grady, Mark Hart, Jeff Ibach, Alex Riggs, Scott D. Young, Jeff Lee, Matt Kimmel, and Jason Nelson.

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