Not enough invitations for all of us to get in? I have an idea.

Most adventurers are fully aware of how much more effective they are working together than alone, but Reagents take “working together” to another level entirely. Fusion is an excellent way to temporarily create super-characters capable of solving problems that normal characters cannot, but it's worth noting that fusion also carries the not-insignificant drawbacks of halving total action economy and spotlight time.

Reagent Fuse with others.
caret-right Garnet Get and stay together more easily.
caret-right Quicksilver Merge and split fast.
caret-right Synergy Ability and weakness bonuses.
caret-right Takeover Merge with the unwilling.
caret-right Troika Three-creature fusions.

Reagent

Utility plus-circleFusion Dance: As a procedure, you can physically fuse with another willing creature to create a single, combined creature that's more powerful than either of its constituents and looks like a combination of both.

plus-circleTime to Make a Platypus: A fused creature's level, combat ratings (Melee/Remote/Whelm), and resource counts (Provisions/Supplies/Mojo) are equal to the sum of its constituents'. Fused creatures have access to every archetype and ability known by their constituents, and are the same size as whichever constituent creature was largest. Flesh/Energy/Attention are equal to whichever constituents' total was lowest at the time of fusion. If either constituent has a weakness, the newly merged creature also has that weakness (but might have more free abilities from it due to their higher level).

minus-circleInventory Squish: Fused creatures still have only 10 inventory slots as normal. All inventory items held by both constituent creatures are merged and held by the new fused creature. This might immediately force the newly-fused creature into heavy encumbrance or even cause them to drop excess items on the ground if they can't hold everything themselves.

minus-circlePlaying Doubles: Fused creatures cannot undergo fusion again.

plus-circleFission: A fused creature can split back into its constituents at any time as an action. Both constituents appear in or adjacent to the space formerly occupied by the fused creature. After fission, both participants are left with Flesh/Energy/Attention equal to whatever the fused creature had and can split up resources as they see fit.

minus-circleAuto-Fission: Fission happens immediately and unavoidably as a free action when a fused creature loses a point of Flesh for any reason.

minus-circleProvisions: Fusing requires you to spend 1 point of Provisions.

Garnet

Utility plus-circleUnsplittable: Fused creatures you're a part of are not automatically split when they lose Flesh. You stay fused until you decide it's over.

plus-circlePracticed Partner: Keep a list of everybody you've fused with. When fusing with somebody you've previously fused with at some point in the past, doing so does not cost any Provisions.

Quicksilver

Utility plus-circleFast Meld: You can fuse with an adjacent creature as a single action instead of taking a full procedure.

plus-circleInsta-Split: You can end a fusion as a free action at any time during your turn.

Synergy

Utility plus-circleEmergence: When both you and your partner have at least one level in the same archetype as each other, the newly-fused combination creature gains a free advanced ability from that archetype that neither of you knew.
Utility plus-circleLatency: So long as only one fusion partner has a weakness, you can decide whether the fused product has that weakness or not.

minus-circleDouble Recessive: If both fusion partners have the same weakness, then the product creature also has to have that weakness too.

Takeover

Utility plus-circleHostile Merger: You can fuse with adjacent creatures that are unwilling. Unless you also have the Quicksilver ability, this generally means they must be unconscious or restrained.

minus-circleDuel of Wills: Your fusion partner will continuously fight you for control over the new form. At the beginning of each exploration turn, roll a trigger die to see who's in control, as follows:
- If your level is at least double your partner's, you are in control on a result of 4+.
- If your level is at least equal to your partner's, you are in control on a result of 7+.
- If your partner's level is higher, you are in control on a result of 10+.
- If your partner's level is at least double yours, you are never in control.

minus-circleTight-Fisted: When you merge with an unwilling partner, you do not gain any access to their resources (Provisions, Supplies, or Mojo).
caret-right Alternative plus-circleStruggle: If you fail your trigger die check to stay in control for a round, you can choose to reroll it as many times as you want and take the best result.

minus-circleMojo: Every time you reroll the trigger die to seize control, you must spend 1 Mojo.

Troika

Offense plus-circleTriple Team: You can perform a fusion with three individuals instead of two. This can be done all at once as a single fusion, or you can meld yourself with one other creature as normal and then add another later on.