- As yet Unknown.
It seems possible that the Arkenhammer is an artifact of changemancy fate magic, as the known powers are to alter walnuts and birds (nut->pigeon, orly->walnut), alter the holder's movement type(ground->air), alter the demeanor of dwagons(aggressive->subservient), as well as their side(Barbarian->GK) and fire lightning bolts(inert state->excessive electrical state). Further, the only known user attuned to it is a pure method of change(piker->warlord->Chief Warlord->Heir->Ruler), whose stated goal is to alter the face of the world(warring states->singular empire). On the other hand, any "effect" could be said to be a change from one state to another and could thus be included in the above list. Virtually the only power that would not fit "changeamancy" would be to do nothing, or to prevent change.
Changemancers may be able to affect the specials of units. Example, changing a certain unit so that it grows wings, giving it the flight special (which may be related to Wierdamancy). Or possibly just the caster, like David Bowie shape-shifting in Labyrinth (the only known Changemancer being named after him).
It is possible that Changemancy can change the state of matter (such as liquid to solid) or its atomic composition (such as lead to gold), making it an equivalent to real-world alchemy. In addition, promoting units (piker to warlord, garrison to field unit) may also be a form of Changemancy, a "refinement of the spirit," rather than of the body. Changes in form of self or others (nut to Orly) could also come under this branch of magic.
In contrast to the cosmology of the the Real World, where time and space are seen as separate dimensions, Changemancy seems to be a discipline composed solely of the element of Matter. The impact of this is unknown.