Rules say that actions on the prompted action table can be done as block moves. Does this mean that ONLY these actions?
Or other things - such as forming an orb - can also be done as block move?

Dismounting and forming orb: Needs clarification, but as an umpire I would permit it as long as all the UGs in the block perform the same action. 

Placing stakes or caltrops is explicitly permitted as a block move and not all the UGs have to be so equipped.

Richard

Nothing on this topic in new compendium claries.