Symbionts
Symbionts are aberrations with the specific symbiont subtype (detailed here). While unattached to a host, they act very much like normal aberrations and can be defeated during an encounter. However, symbionts were specifically designed to act in concert with a host, not on their own. Thus, while individually, they do not pose much of a threat, it is when they are attached to a competent host that their abilities really shine.
Symbionts are designed like intelligent magical items, but they are not crafted, they are grown. By injecting complex chemicals into another non-symbiont aberration over the course of multiple hours or days, what starts as a cancerous tumor eventually matures into a symbiont. Once fully grown, the symbiont detaches from the original aberration and can be attached to a new host.
Creation
The process to create a symbiont is similar to creating an intelligent magical item. While in some situations, parts of the process can be hand-waived, there are situations where it cannot be.
Feats
Even though symbionts can created to be used as weapons, armor or wondrous items, the only feat needed to create a symbiont is the Craft Symbiont feat.
Price
The final price of a symbiont is determined much like other intelligent magical items. Symbionts typically take up a magical item slot requirement, like a normal magical item. Those that are slotless cost appropriately higher. Unlike implants, symbionts naturally know how to attach and detach from their hosts without the need for surgery, thus there is no cost to attach or remove a symbiont.
Cost
The cost in raw materials needed to create a symbiont is complex chemicals, worth one half of the final price of the symbiont.
Talismanic Cost
Symbionts do not have a required talismanic cost, although the necessary host (see Effort) often make the creation process more complicated than usual items.
Time
The time required to make a symbiont is the typical 1,000 gp per day. This time can be reduced as per the normal magical item creation rules, however the strain upon the aberration used to grow the symbiont gets worse if this option is used.
Effort
In order to create a symbiont, the creator must have a willing or helpless aberration that does not have the symbiont subtype for the entire duration of the item creation process. The host aberration can only grow one symbiont at a time and during the creation process, the host aberration suffers 1 point of Constitution drain. Any Constitution damage or drain that the host aberration suffers during the creation process does not heal naturally and cannot be healed without aborting the symbiont entirely. If any process speeds up the time to create a symbiont faster than 1 day per 1,000 gp (either through feats, favored class points, raising the DC, etc), the host aberration suffers a total number of points of Constitution drain equal to one half of caster level of the symbiont, rounded up, with the same limitation on healing.
At the end of the creation process for making a symbiont, the creator needs to make both a Spellcraft check and a Heal check, using the standard item creation DC for both checks. If either check fails, the symbiont dies. Aberrations that create a symbiont using their own body, like the Daelkyr Half-Blood, can substitute their character level for either the Spellcraft check modifier and the Heal check modifier. Once the symbiont is fully grown and detaches, any Constitution drain done by the creation process is turned to Constitution damage and can be healed normally.
Use
Symbionts are used much like other intelligent magical items, with some unusual benefits and complications, detailed below. For obvious reasons, symbionts cannot be attached to creatures with the incorporeal or swarm subtypes.
Benefits
All symbionts have the following benefits.
As One: All symbionts have the standard benefit of As One, as per Special Rules, with the exception that repairing a symbiont is resolving like healing an aberration. Likewise, if the symbiont is killed, it can be raised or resurrected.
Dispel Immunity: All symbionts have the standard benefit of Dispel Immunity, as per Special Rules.
Magic Weapon: All symbionts that can be used as a weapon have the standard benefit of Magic Weapon, as per Special Rules.
Complications
All symbionts have the following complications.
Action Limitation: While attached, a symbiont does not have any of it's own actions (standard, move, free, etc). Any necessary action expenditures come from the host. The exception to this is, if the symbiont feels the need to, it can spend a full-round action that provokes to detach itself from the host, at which point it regains it's normal allotment of actions.
Attachment: All symbionts have the standard complication of Attachment, as per Special Rules. This means that most symbionts take up an body item slot.
Collective Ego: All symbionts have the standard complication of Collective Ego, as per Special Rules. When created, symbionts have the same alignment as their creator and their special purpose to serve whatever host they are attached to. A symbiont that is left unattached to a host for 24 hours immediately changes it's alignment to Lawful Evil and it's special purpose to serving the Daelkyr of Xoriat.
Damage: All symbionts inflict some kind of attribute damage to the host. If the host cannot take that specific kind of damage, the symbiont refuses to attach. While this damage is not permanent, it does not heal naturally and any attempt that heals the damage results with the damage being immediately re-inflicted and the symbiont enforces its Ego complication to make sure that it does not happen again.
Limited Transformation: All symbionts have the standard complication of Limited Transformation, as per Special Rules.
Locked Benefits: All symbionts have the standard complication of Locked Benefits, as per Special Rules.
Locked Size: All symbionts have the standard complication of Locked Size, as per Special Rules.
Recovery: Recovering a symbiont from a slain enemy is a little tricky. If the host dies due to an area effect or an effect that destroys the body, like Disintegrate, all symbionts immediately get any appropriate saving throws or checks, using the host's appropriate modifier, to resist as they detach. If successful, they are treated as separate creatures in any adjacent square to the host, as desired, resolving the initial effect normally. Otherwise, they die with the host.
Designing New Symbionts
Designing a new symbiont is based on the process of designing an intelligent enchanted item, but with some added steps. For ease of reference, follow the steps below.
Designing the Core Item
First and foremost, symbionts are permanent enchanted items. When designing a symbiont from scratch, start with designing the standard permanent magical item that they are supposed to duplicate, but following the limitations below.
Symbionts must be set to a specific size category for the host. By default, all symbionts are assumed to be created for a Medium size host.
Symbionts cannot be based on firearms, alchemical weapons or any weapon that cannot be wielded (like a siege weapon). If the symbiont is based on a ranged weapon, the Returning special weapon quality (for thrown weapons) or the Endless Ammunition special weapon quality (for any other kind of ranged weapon) must be included.
Symbionts cannot be based on items that use any item creation feat other than Craft Magic Arms and Armor, Craft Wondrous Item or Forge Ring.
Symbionts cannot be based on items that have a finite number of charges or uses.
Symbionts cannot be based on items are not designed to be worn or wielded
Symbionts cannot be based on any item that provides any kind of sacred bonus, any effect or quality that would make the symbiont good aligned or any effect or quality that targets aberrations for additional damage or additional negative effects, like Bane (Aberration).
Any material-based damage reduction that a symbiont provides can also be overcome by a byshek weapon.
Symbionts that are created after weapons or armor do not need to have the minimum +1 enchantment bonus to have a special quality.
From this design, you will have the symbiont's magic item slot (or slotless), the starting price, the caster level and the spells and other requirements, as well as the intended host's size category.
Applying Intelligence & Ego
All symbionts are considered intelligent items, following the normal rules for intelligent items (Corebook, pg. 532), with the following requirements.
The standard cost of 500 gp for being an intelligent item is not applied to symbionts.
All symbionts have the same alignment as their creator.
All symbionts have a special purpose, as per the intelligent items rules. This special purpose is to serve and protect the host.
All symbionts get Telepathy (but only with the host), Senses (60') and Darkvision without increasing the cost. Likewise, all symbionts can understand, but not speak, Undercommon and Daelkyr.
Any increases to Intelligence, Wisdom, Charisma or Ego, or other special powers, occurs during this step. Unlike standard intelligent items, any saving throw DCs for spells, psionics or supernatural abilities is always based on the symbiont's Charisma score, not its highest mental attribute.
All symbionts have the a flaw where if they are not attached to a host for 24 hours, their alignment immediately changes to Lawful Evil and their special purpose immediately changes to serving the Daelkyr of Xoriat.
Between the special purpose and the included Telepathy, all symbionts have a minimum Ego score of 3.
By the end of this step, you will have the final price, mental attributes and final Ego of the symbiont.
Creating the Creature
While all symbionts are considered intelligent items, they are also aberrations with the symbiont subtype. Using the item slot that the symbiont occupies and the size category for the intended host, determine the actual size category for the symbiont on the table below.
Once you have the size category for the symbiont, use the following table for initial physical attributes of the symbiont. By default, symbionts use the Poor Movement rate listed, but if the type of magical item that the symbiont is inherently flexible and snake-like (whips, spiked chains, cloaks, gloves, belts, etc), use the Good Movement rate instead.
As aberrations, symbionts use a d8 Hit Die and every symbiont starts with a number of Hit Dice, based on the the table below. Divide this starting HD by 2 for each size category the intended host is smaller than Medium, to a minimum of 1. Multiply this starting HD by 2 for each size category the intended host is larger than Medium. Symbionts based on armor, shields or weapons get an additional +2 HD for each +1 enchantment bonus they have.
As aberrations, symbionts have a medium BAB (3/4 HD), poor Fortitude and Reflex saves (1/3 HD) and good Will saves (2 + 1/2 HD). Likewise, they increase their attributes at the normal rate (1 point per 4 HD), but can only spend those attribute points on Strength, Dexterity and Constitution. Any improvements to Intelligence, Wisdom or Charisma needs to be done as part of the Applying Intelligence & Ego step (see above). If the enchanted item that the symbiont is based on grants an attribute bonus, then the symbiont has that attribute bonus as well.
Symbionts get feat slots at the normal rate (1 at the first HD, plus 1 ever 2 HD thereafter). Typically, symbionts choose the following feats: Alertness, Dodge, Improved Initiative, Great Fortitude, Iron Will, Lightning Reflexes, Skill Focus, Toughness and Weapon Finesse. The host does not get the benefit of these feats. If the enchanted item that the symbiont is based on grants bonus feats to the host, then the symbiont has those feats as well, even if it does not qualify for them.
Symbionts get skill ranks equal to 4 + its Intelligence modifier per HD, with following skills as class skills: Acrobatics, Climb, Escape Artist, Fly, Intimidate, Knowledge (Planes), Perception, Spellcraft, Stealth, Survival and Swim. Symbionts always put the first rank from any Hit Dice into Stealth and the second, if available, into Perception. If the enchanted item that the symbiont is based on grants skill ranks or modifiers, then the symbiont has them as well.
Symbionts usually get a bite attack, appropriate for their size category. Symbionts that are based on ranged weapons or flexible melee weapons (claws, whips, spiked chains) have those type of attacks and are considered proficient with them. Any special ability that the symbiont grants the host (resistance bonus to saving throws, deflection bonus to AC, new or better movement rate, spell-like abilities, supernatural abilities, etc) that does not require a minimum size category or the ability to communicate to use, the symbiont has as well.
If a symbiont is capable of generating a spell, power, spell-like ability or psi-like ability, it uses the caster level of the item it is based on, not the HD of the symbiont itself.
Final Details
All symbionts must inflict 1 point of attribute damage to the host when attached. This attribute damage is what sustains the symbiont. By default, the chosen attribute is Constitution, but if the symbiont provides an attribute bonus, it never inflicts damage to the attributes receiving the bonus. A different attribute can be chosen, but it must fit with the theme and the body slot of the symbiont, usually choosing Strength or Dexterity for weapons, armor or items in the hands, wrists, chest, body, belt and feet slots, Wisdom or Intelligence for items in the head, headband, neck, shoulders or ring slots, or Charisma for items in the eyes / face slot.
The final CR of the symbiont is largely inconsequential to use of the symbiont, but unless the symbiont has a good movement rate and/or access to ranged attacks, it should be 1 to 2 CR less than a normal aberration of the same hit dice.
Examples
The following are examples of symbionts already in this conversion.