The official flanking rules in the are short and sweet. There’s an explanation of them on p197 of the Core Rules (2009) and a nice diagram on p196. Both are grouped together in the excellent Pathfinder PRD.
The official rules state that in order to flank a foe two allied characters must threaten that foe from opposite sides of the foe’s square. As you imagine a rule like that is never going to wash in a system that doesn’t use a combat grid. For years we’ve been using the same house rules to cover Flanking. It is simple and easy to remember, and here it is:
- If you are engaged in mêlée combat and you also outnumber your foe(s) by a ratio of 2:1 then you are considered to be flanking those foe.
- Creatures with a Reach of zero (Fine, Diminutive and Tiny creatures) cannot flank.
Obviously the 2:1 ratio means that two or more allies need to be attacking the same opponent in mêlée. The advantage of this rule is that it’s really easy to implement and everyone remembers it. In fact it’s served us so well over the years that I don’t really feel a great need to change it.
I just want your opinion on whether you think the size of the opponent should play a role in things. The 2:1 ratio might be right if two humans attack another human, but should two humans be able to flank a giant, or a treant or a dragon? I think it’s fair that two Medium-sized creatures should probably be able to flank a Large creature… but when you get to creatures that are Huge or bigger I become less certain of the mechanic.
I desperately don’t want to make flanking any more complicated. If it’s not broken then I don’t want to try fixing it. But at the same time I want a game that’s fair. So what do you think?