Fusion magic is the result of two or three Casters linking through a Thinkamancer in order to create a whole greater than the sum of its parts. The linked Casters can perform Spells far more powerful than any single Caster could consider possible. Casters united in this away are said to be linked.
A Thinkamancer joins with one or two other Casters to create a combined consciousness. The process of creating the link involves each Caster recalling how it felt when it first cast a Spell of its Discipline, which is described as warm, comforting, and familiar.Erf-b1-p135 The casters then lose their individuality and revert to representing only their Discipline. It is still possible for a Caster to remember its former existenceErf-b1-p046, but using this knowledge strains and might break the link.Erf-b1-p054 The link is fragile, and can be broken by merely calling one of the Casters by its name, so the linked Casters are referred to by their Disciplines instead (ie. Thinkamancer, Dirtamancer, Lookamancer, etc.).
Breaking the link can result in damage to the minds of the Casters, but this is similar to the backlash of other Thinkamancy Spells, so a good Thinkamancer can protect herself (or himself) from the damage by forcing the other Casters to bear the brunt.Erf-b1-p084. This can lead to insanity of the other Casters and in the extreme case death Erf-b1-p077
- Uncroak volcanoesErf-b1-p135 and control the direction of the blastErf-b1-p142
- Enhanced perception of terrain (leading to gem finding)Erf-b1-p142
Sizemore says that some sides combine Mathamancy and Luckamancy Erf-b1-p054. This could just mean that they work together, rather than as a formal linkup. However, Sizemore explicitly compares the combination to the Eyemancer linkup.
- Targeted Luck: The Mathamancer determines the most important battles and the Luckamancer tilts them in his sides favour.