Does a Magician have to bespell the nearest enemy?
No. Note that there is no line of sight requirement for bespelling, that the target (but not the Magician) can be in combat or overlapping, and that a Magician can bespell in any direction. When assessing the result of bespelling attempts, do elements in contact with the target influence the result? Yes. For example, a friendly Warband is in contact with an enemy Blade. You bespell the Blade and beat it. Ordinarily the Blade would recoil, but as the Warband is the most dangerous element to the Blade, and is in contact with it, the Blade is destroyed.