Apologies if I'm posting about an already done and dealt with topic, but after (what I thought to be) a fairly thorough search I haven't been able to come up with any explanation as to how the Robb Stark House Card is supposed to work.
The gist of the problem is explained in this topic on BoardGameGeek (scroll down to Robb Stark under House Cards); apparently you can override the rule found on page 21 of the rulebook that states "If the attacker lost the combat, his surviving units must retreat back to the area from which they marched" and make your opponent retreat to any other area. This seems to be at odds with the text on the House Card itself, which says that you must select a legal area where your opponent would lose the fewest units.
My question is this: if you're supposed to select a legal area for your opponent to retreat to, and the "official answer" on BoardGameGeek says you can select an apparently illegal area, which kind of "legal" are we talking about? Does it mean legality regarding the choice of area, the player controlling the area you wish your opponent to retreat to (i.e. could you make him retreat to an area you have a Power Token on?), the type of border (could you make him retreat across a river?) or… what?