Plant Symbionts

Symbionts are custom-grown plant creatures tailored to serve specific purposes, like living tools. There are myriad forms of symbionts that serve mundane purposes, like mobility enhancing exoskeletons to assist erahthi who possess difficulty walking or lifting heavy objects, communication symbionts that can relay messages, even clothing that sizes itself to fit its wearer and protects against parasites and pests. This section focuses on combat-oriented symbionts.

Creatures of all species can create plant symbionts, and some have even begun to experiment with creating symbionts of other creature types, like aberrations and elementals. Symbionts are created in special laboratories and each have a monetary cost associated with them like magic items.

Creating Plant Symbionts

Creating a plant symbiont is similar to creating a magic item. To create a plant symbiont, a character must possess the Create Plant Symbiont feat. The intensive process requires a character to spend at least 8 hours a day per 1,000 gp (or au in the Aethera Campaign Setting) of the plant symbiont’s cost attending to the feeding and cultivation of the growing creature.

Spending additional time does not decrease the time it takes to create a plant symbiont. The cost of the plant symbiont represents the various materials used in its creation—the specialized tanks, mineral-enriched water, various temperature devices, and food. To grow, the plant symbiont needs at least 12 hours a day of constant light, either natural or specially created grow lamps (included in the base cost). If the character does not spend the 8 hours a day or provide the 12 hours of sunlight, the fledgling plant symbiont begins to wither and die. Each day these conditions are not met until the cost of the plant symbiont is reached, there is a 10% cumulative chance the plant symbiont dies. Plant symbionts are assumed to be created for a medium-sized host. Plant symbionts for larger hosts require an additional 50% of the plant symbiont’s cost for each additional size category. At the end of the process, the player must succeed on a Symbiont Handling check equal to 10 + the plant symbiont’s Hit Dice. On a failure, the plant symbiont is not successfully created and all the materials and costs associated with its creation are lost. The player cannot be assisted by another creature in this attempt.

Players are encouraged to create new plant symbionts. First, players should work with their GM to determine the exact powers and cost of a brand-new plant symbiont. The GM has the final say in what the powers and cost are. It is advised that players compare the plant symbiont to other similar magic items to derive the appropriate powers and cost. Additionally, plant symbionts differ slightly from magic item creation in that they must follow separate rules.

  • Plant symbionts must use a slot on the body as per the magic item rules for slotted items. The plant symbiont’s host abilities should match the slot on the body that makes the most sense (for example, a plant symbiont increasing a host’s base speed would likely occupy the feet slot instead of the neck slot).
  • Plant symbionts can only provide alchemical, armor, circumstance, dodge, enhancement, insight, natural armor, and resistance bonuses. They cannot provide sacred, profane, or any specific racial or magical bonus.
  • Plant symbionts cannot have a finite number of uses or charges.
  • Plant symbionts cannot be created in conjunction with magic item creation feats.
  • A plant symbiont’s total price cannot exceed 105,000 gp/au and a CR of 6. Symbionts above CR 6 are considered artifacts and beyond the capabilities of players to create.
  • Plant symbionts are always creatures of the plant type with the plant symbiont subtype.

Determine Size

A plant symbiont’s size corresponds with the type of slot it occupies. Because a plant symbiont is an organic creature, usually composed of roots and numerous vines which wrap around the host, it may, if the character desires, be one size category larger than the standard size listed below (which assumes a medium sized host—adjust one size category up for each size category of the host creature). It still assumes the size listed on the table when it bonds to a host but assumes its larger size when it is not attached.

Slot Size
Belt Tiny
Body Small
Chest Small
Eyes Fine
Feet Tiny
Hands Diminutive
Head Diminutive
Neck Diminutive
Ring Fine
Shoulders Small
Wrists Diminutive

Determine Challenge Rating

Every plant symbiont has a challenge rating based on its total price (its cost x2). The challenge rating is to assist the player and GM in generating the plant symbiont’s monster stat block and powers.

CR Price (gp/au)
1 1,000–5,000
2 5,001–15,000
3 15,001–30,000
4 30,001–50,000
5 50,001–75,000
6 75,001–105,000
Table: Symbiont Statistics
CR hp AC Atk High Atk Low Dmg High Dmg Low Ability DC Primary Ability DC Secondary Save Good Save Poor
1 15 12 2 1 7 5 12 9 4 1
2 20 14 4 3 10 7 13 9 5 1
3 30 15 6 4 13 9 14 10 6 2
4 40 17 8 6 16 12 15 10 7 3
5 55 18 10 7 20 15 15 11 8 4
6 70 19 12 8 25 18 16 11 9 5

Create Symbiont Stat Block

The last step is to create the plant symbiont’s stat block.

Monster creation is not an exact science, however, and the player and GM are encouraged to work together in developing it, using the rules for monster creation and applying the plant symbiont subtype. The guidelines use an average of where its stats should fall.

Once you generate the plant symbiont’s general stats (AC, hit points, attacks), develop one or two primary special abilities or attacks for it. These abilities should tie in thematically with the abilities it grants to its host.

It is a good idea to compare the finished plant symbiont stat block to other monsters of a similar CR as well as one CR above and below to ensure the plant symbiont is appropriately balanced. GMs are encouraged to work with the player to adjust the plant symbiont’s stat block if, during play, it’s too weak or too strong.

As plant creatures, plant symbionts gain d8 Hit Dice, have a 3/4 Base Attack Bonus, and good Fortitude saves as well as the following traits:

As a plant creature, the plant symbiont uses the following table to determine its approximate number of Hit Dice. Remember, these aren’t hard numbers but guidelines.

Table: Plant Symbiont Hit Dice
1 2
2 3
3 4
4 5
5 7
6 9

Additional Options

The engineering of plant symbionts allows a lot of room for experimentation. Particularly among non-erahthi, the creators of plant symbionts have become known for the unique elements in their designs. Some of these are trade secrets and jealously guarded, while other techniques benefit from wide distribution. It is up to the GM to decide which of the options listed below are immediately known to the players. While a character may have heard of a new way to create plant symbionts—knowing and actually being able to utilize the option can be entirely different.

The following options can be used to customize plant symbionts to the creator’s taste. Any number of options can be chosen when creating a new plant symbiont. These options cannot be used on a plant symbiont that has already been created.

Cost: The additional cost is a percentage of the original base cost. For example, a player creating a plant symbiont normally costing 1,000 gp/au and adding the advanced and camouflage options will create a plant symbiont costing 1,650 au (500 au for the advanced option and 150 au for the camouflage option).

DC: Adding options increases the DC of the Symbiont Handling check used to create the plant symbiont. DCs from multiple options stack.

Table: Plant Symbiont Options
Option Cost DC
Ability Increase 20% 3
Advanced 50% 4
Camouflage 15% 2
Feat 30% 3
Regeneration Increase 30% 4

Ability Increase: The plant symbiont has one physical and mental stat (except Intelligence) increased by +2.

Advanced: The plant symbiont creature gains the advanced creature template. This allows a player character to advance a CR 6 plant symbiont to a CR 7.

Camouflage: When bonded, the plant symbiont changes its color and shape to match the host’s clothing.

The plant symbiont retains all its properties (including weight) when it is so disguised. It can be detected through magical means, such as true seeing, as well as a Perception check with the DC = 20 + the plant symbiont’s Hit Dice.

Feat: The plant symbiont gains one of the following feats as a bonus feat: Improved Initiative, Toughness, or Weapon Focus. The option can be selected more than once but each time, it selects a different feat.

Regeneration Increase: The plant symbiont regenerates faster at a rate of three times its total Hit Dice.


Creating new plant symbionts, whether by a player character or GM, represents the growing diversity in this field of science. To summarize, these are the following steps to create new and different plant symbionts:

  1. Develop the types of host abilities the plant symbiont has.
  2. Determine the cost of the plant symbiont by comparing it to existing, similar magic items.
  3. Decide the slot on the body the plant symbiont will occupy.
  4. Select additional options for the plant symbiont or items used in its growth.
  5. Pay the cost of the new plant symbiont and the time taken to grow it.
  6. Determine the plant symbiont’s CR.
  7. Generate the plant symbiont’s stat block and special abilities. Remember to compare it to existing monsters to aid in balancing it.

Plant Symbiont Statistics

Plant Symbiont Skills and Feats

Symbiont Handling (Handle Animal; Skill Unlock)

Though they are mindless creatures, you can teach plant symbionts (as described in the Aethera Campaign Setting and Alien Bestiary Companion) different commands through the empathic link formed by bonding with them. The type of commands symbionts can learn are relatively simple.

This skill unlock is only available to characters with the Symbiont Handler feat.

Check: The DC to train a symbiont a trick depends on the complexity of the command.

Handle a Symbiont: This task involves commanding a plant symbiont to perform a command that it knows. The plant symbiont must be bonded to you for at least 1 round for you to be able to communicate the command. The plant symbiont performs the command to the best of its ability until you bond with it again.

Table: Symbiont Handling
Task Symbiont Handling DC
Handle a plant symbiont 10
Teach a plant symbiont a command 15 or 20*
Section 15: Copyright Notice

Alien Codex © 2018, Legendary Games; Lead Designer: Jason Nelson. Authors: Anthony Adam, Kate Baker, John Bennet, Eytan Bernstein, Robert Brookes, Russ Brown, Duan Byrd, Paris Crenshaw, 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, Jeff Provine, Alistair J. Rigg, Alex Riggs, Wendall Roy, Mike Shel, Neil Spicer, Todd Stewart, Russ Taylor, Rachel Ventura, Mike Welham, George Loki Williams, Scott Young.

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