As an action, you and another willing, living, creature of the same or smaller size fuse into one being. As the caster, you control the actions of the fused being. However, you can give up this control to the other creature. Once you give up control, you cannot regain it unless the other creature relinquishes it. The fused being has your health plus the other creature’s health. The fused being knows all the maneuvers and spells you and the other creature know, has prepared any concoctions you or the other creature has prepared, and has the sum of your and the other creature’s catalysts, mana, and stamina dice. Likewise, all feats, abilities, and class features are pooled (if both creatures have the same ability, the fused being gains it only once).
For each of the six abilities, the fused being’s ability is the higher of yours and the other creature’s. The fused being uses the higher proficiency bonus, saving throw proficiency, and skill proficiency of either member.
You decide what equipment is absorbed into the fused being and what equipment remains available for use. These fused items are restored once the spell ends.
When the spell ends, the fused being separates. The other creature appears in an area adjacent to you that you determine. If separation occurs in a cramped space, the other creature is expelled through the Astral Plane, finally coming to rest materially in the nearest empty space and taking 1d6 points of damage for each 3 meters of solid material passed through.
Damage taken by the fused being is split evenly between you and the other creature when the spell ends. In a like manner, the fused being’s remaining mana is split between you and the other creature (you cannot leave with more than your maximum allowed).
If a fused being is killed, it separates into its constituent creatures, both of which are also dead. You cannot use fission on a fused being.