The REG states in Fortify or Place, Special Conditions:
If a demon is placed on a site where access is possible while Three Nails is activated, the demon is prevented from being ignored and may not be banded into battle if a rescue attempt at that site is attempted. However, once the demon has been on the site for one turn, its special ability to fortify the site cannot be negated on subsequent turns. The demon can be banded even if Three Nails is activated on the later turns.
I think that CBN doesn't relate to ignore at all in this situation. Is this quote outdated?
