Edit: Don't have a screenshot of the display on the promotion, but it reads: "Leash Range : X". Only description I could come up with that is clear, and accomodates negative values.
Something that gives an idea about where the leash is fixed would be nice too. Even if it's just a number indicating how far the unit is from the fixed point.
By the way, is it manhattan or cartesian distance? And can a promotion have a leash range of 0, thereby working as a Held variant?
Edit: I meant Chebyshev distance or Cartesian distance of course.