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Zyoselak CR 12

A transparent, gelatinous mass distends and distorts as it floats through the air; a shoal of minuscule matter, suspended throughout yet moving within it, flows into tendrils of ooze that extrude from the central clot.

XP 19,200
NE Large aberration (swarm)
Init +8; Senses blindsight 60 ft., darkvision 60 ft.; Perception +22


EAC 26; KAC 27
Fort +11, Ref +11, Will +17
Defensive Abilities gelatinous shield, swarm defenses; DR 10/magic; Immunities acid, cold, electricity, ooze immunities; SR 23
Weaknesses vulnerable to sonic


Speed fly 30 ft. (perfect)
Melee swarm attack (1d12+13 A & B plus mind ablation)
Multiattack 4 slams +17 (1d12+13 A & B), swarm attack (1d12+13 A & B plus mind ablation)
Space 10 ft.; Reach 10 ft.
Offensive Abilities distraction, engulf


Str +1, Dex +8, Con +4, Int +5, Wis +3, Cha +1
Skills Acrobatics +22, Bluff +22, Physical Science +27, Mysticism +27, Sense Motive +22, Stealth +22 (+27 while in gelatinous shield)
Languages Abyssal, Aklo (cannot speak); telepathy (within swarm’s area)
Other Abilities abhorrent mind, accelerated assimilation, no breath, separate, transparency control


Abhorrent Mind (Ex)

Mind-affecting effects that target single creatures function normally against a zyoselak, since the creature’s individual components share a hive mind. Due to the alien nature of its hive mind, however, a zyoselak gains a +4 bonus on saving throws against mind-affecting effects, and whenever it succeeds at a save against a mind-affecting effect, the opponent attacking it with that effect must succeed at a DC 21 Will save or be Stunned”>stunned for 1 round.

Accelerated Assimilation (Ex)

The acid of a zyoselak’s gelatinous shield breaks down flesh and bone into nutrients that the zyoselak absorbs.

Whenever a gelatinous shield deals acid damage to a target made of flesh or bone, a zyoselak within it heals an equal amount of damage. If a creature dies while engulfed by a gelatinous shield, its flesh and bone is completely consumed at the end of the zyoselak’s next turn, providing the swarm with 16 hit points of additional healing.

A creature that has been completely consumed can only be returned to life by magic that does not require a piece of the creature’s body, such as miracle and wish.

Acid (Ex)

A zyoselak’s gelatinous shield dissolves and digests only flesh and bone; creatures and objects not made of flesh or bone are immune.

Gelatinous Shield (Ex)

A zyoselak secretes and inhabits a mass of acidic, paralytic jelly which it uses for both offense and defense. A zyoselak telekinetically animates and levitates the gelatinous mass, enabling it to continue to fly while within it (albeit at half speed) and extrude dexterous pseudopods with which to make slam attacks.

Although a zyoselak is a swarm of Fine aberrations, while it is in a gelatinous shield it is treated as a Large aberration as it does not function as a true swarm. It retains most of its swarm traits, but loses its vulnerability to area effects, and susceptibility to high winds. It can only make a swarm attack against creatures that it has engulfed. It gains immunity to electricity, 4 slam attacks and the engulf special attack. A zyoselak uses its Charisma as its Strength score, and its Intelligence as its Dexterity score while in a gelatinous shield.

A fully-formed, undamaged gelatinous shield has 50 hit points. Damage to a zyoselak in a gelatinous shield is split equally between the swarm and the shield. The shield is immune to piercing and slashing damage, and the swarm is immune to all weapon damage. If the shield is reduced to 0 hp, it liquefies and falls harmlessly to the ground. As a full-round action, a zyoselak can secrete enough jelly to increase a shield’s current hit points by 1 (to a maximum of 50).

If a zyoselak’s gelatinous shield has been destroyed, it can create a new one with 1 hit point in 1 minute.

A zyoselak can change the transparency and color of a gelatinous shield that it is touching as a free action. A transparent shield is difficult to discern. A DC 15 Perception check is required to notice a motionless gelatinous shield. Any creature that fails to notice a gelatinous shield and moves into it is automatically affected as if the zyoselak had hit with its swarm attack.

A zyoselak inside an opaque shield has total concealment“>concealment but opponents that can see the opaque gelatinous mass nevertheless know which squares the zyoselak occupies.

Mind Ablation (Su)

Creatures whose spaces are occupied by a zyoselak at the end of its move must succeed at a DC 21 Will save or take 1d4 points of Intelligence damage as the creature psychically erodes their minds. This is a mind-affecting effect.

The save DC is Charisma-based and includes a +2 racial bonus. Each time a zyoselak causes Intelligence damage to a creature, the zyoselak gains 5 temporary hit points. These temporary hit points stack to a maximum 40. As a standard action, a zyoselak can use its mind ablation ability as an 80-ft. Line“>line or 40-ft. cone. It can use this ability up to five times per day.

Separate (Ex)

If a zyoselak moves outside of its gelatinous shield, the gelatinous shield liquefies and falls harmlessly to the ground. Without the zyoselak configuring its shape from within, the gelatinous shield becomes a sphere. As a standard action, the zyoselak can telekinetically move the sphere up to 30 feet.

Outside of a gelatinous shield, a zyoselak functions as a true swarm; its statistics change as follows: CE Fine aberration (swarm); Defensive Abilities swarm defenses; Immune acid, cold, swarm immunities; Speed fly 60 ft. (perfect); Melee swarm (4d6 plus mind ablation); Special Attacks distraction (DC 21).

If the zyoselak does not move back into the gelatinous shield within 5 rounds, moves farther than 80 feet away from it, or otherwise wills it as a free action, the shield liquefies and collapses.

A zyoselak can only maintain one gelatinous shield at a time.


Environment any
Organization solitary or audience (2-3 zyoselaks)

A zyoselak is a hive-mind swarm of thousands of minute organic entities, each of which is a specialized element of the creature, unique in appearance—most commonly resembling viruses, pollen, or eyes—and sized no more than an inch or so in diameter, but typically less. Each individual unit of the creature houses a brain with a limited, autonomous intelligence, but together, the swarm acts as a large, telepathic neural network—each node of which is a brain itself—with an emergent mind capable of highly advanced reasoning and learning but also indecipherable and unpredictable behaviors that seem to focus on inventive, extreme, and unusual cruelties with which to torture other forms of sentient, organic life.

The ‘voice’ of a zyoselak is a telepathic cacophony of confusing and chaotic contributions of opinion, the most prevalent of which tend to be the most discernibly coherent amongst the noise, but there is not always a prevailing view. In this case, the creature might communicate in a number of parallel voices, each of which conveys a stream of distinct, perhaps contradictory, information. A conversation with a zyoselak can therefore be an extremely difficult endeavor, not to mention the fact that the range of its telepathy is limited to the area within its swarm and so communication is often accompanied by physical and mental assault by the creature which fails to appreciate or care for the objections that other beings have to this behavior.

As well as contributing its petty and selfish votes within the distributed decision-making apparatus that drives a zyoselak’s aberrant conduct, and performing one or more functions for the collective—perceiving with its alien equivalent of an eye, ear, nose or tongue, perhaps; breaking down flesh and bone with protrusions like teeth, knives, saws, or pincers; reconstructing, reconstituting, or birthing individual units from the remains of those destroyed and other assimilated organic matter—each entity in the swarm is also capable of excreting an acidic, paralytic jelly that it telekinetically manipulates for both defensive and offensive purposes. Although it slows the psionic flight of the zyoselak, this gelatinous bubble shields the swarm from physical and electrical attacks while providing a vehicle with which to engulf and entrap creatures, or attack them with powerful, paralyzing slams.


Zyoselaks are an extremely rare and advanced type of alien life that evolved on a distant world in response to a set of unique, environmental pressures that forced them to form collective gestalts and which were subsequently infused with mythic power through prolonged exposure to the body and aura of a god-like ooze that still lies inert in the crushing, freezing depths of an acidic ocean. The supragenius intellects that eventually resulted, which manifested preternatural forms of telepathy and telekinesis, coincided with an utter negation of morality and empathy for other living things.

A zyoselak that manages to acquire a steady supply of flesh, blood, and bone that it can consume over several weeks or months without having to move much or repair itself can replicate until it is a Huge swarm. Soon after reaching Huge size, a zyoselak splits into two Large zyoselaks.

Habitat And Society

Zyoselaks are at once solitary and highly social creatures. They are solitary in the sense that an individual zyoselak tends not to associate with other zyoselaks except on rare occasions when they have a, typically inscrutable, common purpose. But zyoselaks have no community or culture to speak of, and as autophages and cannibals, are as likely to attack each other as they are other creatures.

They are social in the sense that each zyoselak is a collective intelligence with a continuous, internal array of discussions that range from the trivial to the deeply philosophical—a fact that makes their apparently universal rejection of morality all the more chilling—and whose behavior is regulated by its constituent entities through a type of proportional representation electoral system.

Rare even on their homeworld, zyoselaks are virtually unknown elsewhere. Still, powerful conjurations can and have opened interplanar portals and interplanetary gates that have enabled them to cross into other realms where they prefer to lurk deep beneath the surface, devastating endemic ecologies while randomly roaming through abysmal caverns and sunken seas.

Section 15: Copyright Notice

Alien Bestiary (Starfinder) © 2018, Legendary Games; Lead Designer: Jason Nelson. Authors: Anthony Adam, Kate Baker, John Bennet, Eytan Bernstein, Robert Brookes, Russ Brown, Duan Byrd, Jeff Dahl, Robyn Fields, Joel Flank, Matt Goodall, Robert J. Grady, Jim Groves, Steven T. Helt, Thurston Hillman, Tim Hitchcock, Nick Hite, Daniel Hunt, Mike Kimmel Marshall, Isabelle Lee, Jeff Lee, Lyz Liddell, Jason Nelson, Richard Pett, Tom Phillips, Alistair J. Rigg, Alex Riggs, Wendall Roy, Mike Shel, Neil Spicer, Todd Stewart, Russ Taylor, Rachel Ventura, Mike Welham, George Loki Williams, Scott Young.