Let's say we have two spirits fighting each other: For instance an allied spirit vs. another random spirit or vs. a wyter, or the regimental wyters of two mercenary units:
If one of the spirits gets low on magic points, tries to disengage but does not succeed in that round's spirit combat roll, then it won't be able to disengage (RQiG p.370). it is clearly in trouble! But what sort of trouble?
Such a losing spirit could be reduced to zero magic points. In that case, can it be controlled by the winning spirit? I ask because unless I'm missing something, the rules only speak to control of a corporeal being by a spirit (p.370, possession), or control of a spirit by a discorporate shaman (p.368), or a corporate person binding a spirit using Spirit Binding magic (RQiG p. 249, p.265).
Or does the losing spirit simply retreat into the spirit world, to gradually recover its MPs? What if it is a wyter, which is incapable of recovering its own magic points (RQiG p.287, first full paragraph)?