As written it seems like there are several holes in the Flanking rules that lead to really weird results. I was hoping that someone could provide insights or ideas on this.

The first issue I ran into was "Faerie Rogues". I wondered how flanking would work for them and then I found this line:

Creatures with a reach of 0 feet can't flank an opponent.

This is really weird, It means that a Tiny can only flank if they have a reach weapon. Not sure how scales to Diminutive. It means that a pair of Diminutive creatures cannot flank a Tiny creature. That seems odd because they have the same relative size difference as two Smalls and a Medium.

There's also the inverse problem: can a pair of Medium creatures really flank a Gargantuan creature? Isn't there a size difference at which flanking basically becomes irrelevant?

Is there a specific reason for this behavior?

Is this just lazily filling a hole in the rules?

Does anyone have a more rational set of house rules they apply?


6 Answers 6


The rules for combat in D&D do start to break down in various places when you start dealing with very small or very large creatures and as you've observed, one of these places is flanking.

I'd guess the reason flanking works this way is simplicity. It's a lot easier to say you need to have reach to flank and be on opposite sides than to have special cases around small and large creatures (which would have to take relative size, not absolute size in to account and D&D avoids that wherever possible - just look at how the AC and attack bonuses for size normalise things to be medium). Most of the time the existing rules work just fine.

This is partially because PCs are normally medium or small, monsters are normally a bit bigger than them but not gargantuan and making things more complicated for things that don't come up very much doesn't really add to the game. Additionally, for very large creatures they've already got a sizeable penalty to AC from being so large and normally they have a pretty huge number of hit points. They normally are tough because they can take the hits, rather than because they are hard to hit and because of this don't care much about their AC. A flanking bonus isn't worth anything if you're already hitting reliably without it (unless you're dealing precision damage, but then isn't darting under the gargantuan dragon and stabbing it in the weak point where it's missing a scale just what a rogue should be able to do?).

Then again, if you're running a campaign where this oversimplification will cause problems, possibly because you've got a tiny or diminutive PC or because you're going to be fighting lots of them, you might want to make some changes to bring back some realism.

One easy tweak to make is to say you can flank a creature if you threaten them. If you're two diminutive creatures flanking a tiny creature and you're all in the same square the flanking works fine. This does make it hard to work out who's where in the one square as you still need to be on opposite sides of the creature so maybe scale up the size of everything in a small scale fight. For example, if you've got 3 tiny adventurers fighting 7 diminutive creatures just make the tiny creatures medium for the fight and the diminutive creatures small. The grid rules work fine, you assume people who are fighting are in the same 5ft square so can hit each other (0ft reach) and anyone with a reach weapon still gets the benefit.

If you want to make things a bit more complicated you could say you can only flank someone if you can reach the centre of the creatures space. A medium creature can flank a large creature with a normal weapon but they need a reach weapon like a spear to effectively flank a huge creature. This means you won't flank many larger creatures because you'd need two characters to both have the reach weapons to get a flank. To fix this you could say two characters can flank a creature if their combined reach crosses the creature.

Now two medium creatures with normal weapons can flank a large creature, one of them needs a reach weapon to flank a huge creature and they both need reach weapons to flank a gargantuan creature.

This really penalises rogues and other classes that rely on precision damage as they don't tend to have reach weapons and if they can't flank they won't be able to pull off a sneak attack. There are already plenty of things in the game that stop rogues having fun (plants, elementals, undead, constructs, and oozes to name a few) so they really don't need any more. As @Carcer points out below, Pathfinder did away with a lot of the immunities to precision damage that various creature types had in 3rd ed so rogues have less things interrupting their fun than they used to. It's worth remembering that Pathfinder made this change for a reason though, and introducing these flanking changes will still unfairly penalise precision damage classes while most likely not changing that much for others.

You could fix this by allowing rogues and other precision damage classes to use the old flanking rules to determine if they can get sneak attack damage but still requiring sufficient combined reach to get the +2 bonus.

It does all get rather more complicated though and at the end of the day I'd still say the existing rules, flawed though they are, are probably the easiest and most balanced way to handle things. Just don't play a tiny rogue.

  • \$\begingroup\$ I think the need to reach the center of a space (effectively a limit of a single size category larger in most cases) is a little over-harsh. Rogues are shafted really hard by that rule. The rogue hiding in the huge beasty's blind spot and hitting a weak point is such a huge trope, and the combat presence of a rogue so tenuous as it is, that I wouldn't want to so dramatically increase the number of things that are hard to Sneak Attack. \$\endgroup\$
    – KRyan
    Commented Apr 23, 2014 at 19:51
  • \$\begingroup\$ "There are already plenty of things in the game that stop rogues having fun (plants, elementals, undead, constructs, and oozes to name a few) so they really don't need any more" - this question specifically tags Pathfinder, which did away with the majority of "immune to precision damage" qualities most of those monster types had in 3e. Only elementals and oozes are generally immune to sneak attacks in PF. (Incorporeal creatures ignore precision damage unless dealt by a Ghost Touch weapon - and I would rule other incorporeal creatures could affect them fully in the same way). \$\endgroup\$
    – Carcer
    Commented Mar 30, 2017 at 7:54

Maybe my interpretation is off, but I never considered flanking to be about "where" you strike a foe, but about the fact that they can't watch both of you at the same time. Making an attack against an opponent that can't see you to react is the source of the bonus. This is consistent with the rule for All-Around Vision. This means it's perfectly reasonable to flank a huge creature, in fact it happens in fiction all the time. Also, if the dragon can get a claw on either side of you, you're certainly at a disadvantage, so I can see how larger creatures that can occupy flanking squares around a foe could get the bonus.

The reason those small, "reach 0" creatures can't flank is that they don't threaten a square unless they're in it, so the target doesn't have to watch out for them. This would be fine, except that once you're all in the same square there's no accounting for position. So, once they get close enough to be a threat, the system can no longer account for where they are, and flanking goes out the window.

To correct this problem, I'd try a house rule that says that if you're sharing a square with another creature (aAnd you're both corporeal ...don't really want to go down that rat hole) you need to declare which adjacent square you're closest to, i.e. who's on what side of whom in the square. Then you can use the positioning rules with respect to that creature specifically, like flanking, as though you were in the adjacent square.

  • \$\begingroup\$ So if a medium creature had two tiny opponents sharing the same square with it, and they designated opposing squares, they could flank it? I like it. \$\endgroup\$
    – Jason_c_o
    Commented Apr 22, 2014 at 5:46
  • \$\begingroup\$ And the I guess changing their positions would follow the same restrictions as though they were moving in the spaces around the target, with the exception that they're not restricted by the occupants of those squares, although I suppose they'd subject themselves to AoO from those creatures as they moved. Of course, if you stuff too many little creatures into this model, I suspect it'll come apart in your hands. ;-) At that point, anybody in the mix who has an ally is probably flanking everybody else... \$\endgroup\$
    – Zimul8r
    Commented Apr 22, 2014 at 13:57

Scaling is hard. D&D, and most other RPG systems, are designed for human sized creatures. Get too far away from the average, and weird stuff starts to happen. In D&D, but also in any other system that tries to model scale (except maybe Fudge? I recall that these scale issues were a big part of the inspiration for that).

If you really want to handle stuff at an extreme scale in detail, the best solution is probably to rescale, making the most common size medium, and scaling everything around that. But which size you pick as the new medium will still have impact: medium versus small is different from large versus medium.

Or just accept that D&D doesn't handle everything right, and move on. There are many, many areas where the rules of D&D make no sense whatsoever from a realistic perspective. It's a game system, and not a very simulationist one at that.


The problem

It ultimately comes down to the granularity of the grid.

D&D and pathfinder divide space into 5 foot squares, and then measure all distances in multiples of these squares. This is pretty convenient in the normal course of things. A medium sized creature in combat controls a single square, a large creature fills 4 squares, and so on.

As you've noticed, it breaks down when dealing with distances smaller than a single square, because that's what ultimately is causing problems here. Tiny creatures can't flank because they don't threaten, and they don't threaten because they don't have reach, and they don't have reach because their "real" reach would be significantly less than a single square. So we say that they have to enter a creatures square to attack, which becomes really weird if two Tiny creatures are locked in combat.

Fixing it

To sensibly model combat between lots of Tiny/etc creatures, you need to change the size of the grid. Splitting each 5' square into quarters or ninths (depending on just how small the creatures are) is probably what makes the most sense.

  • If you split it into ninths, you could make a small creature take up 4 of the tiny squares, while a medium one takes up 9. Tiny and Diminutive creatures would take up one square, just like Medium and Small creatures do now. You're essentially scaling down by two degrees, so you can handle reach/etc by this analogy: Medium->Huge, Small->Large, Tiny/Diminutive->Medium/Small.

  • If only some of the creatures are tiny, you could just give them each a quarter of a square, and leave Medium/Small creatures taking up four squares each.


d20 rules were never meant to offer a full realistic model for combat, and it shows in situations like this.

You ask if a medium creature can really flank a gargantuan creature, I ask the inverse, can a gargantuan creature really flank a medium creature? Seems to me like it becomes pretty irrelevant which side of a creature you hit when your weapon is bigger than they are.

If I were to house-rule this, I'd most likely go for something along the lines of:

  • You can always flank a creature that is the same size as you, or differs by 1. If the creature differs 2, roll a d20 every time you check to see if you are flanking, 1-10 you are not, 11-20 you are.
  • If you differ 3, 1-15 you are not, 16-20 you are.
  • If you differ more than that, flanking becomes pretty much irrelevant/impossible.

With the d20 roll "showcasing" the difficulty of flanking a creature with a drastically different size.

  • 2
    \$\begingroup\$ I'd argue that a Gargantuan creature, possibly threatening all squares around a Medium, could conceivably flank it by itself :D \$\endgroup\$
    – Nigralbus
    Commented Apr 18, 2014 at 9:30
  • \$\begingroup\$ @Nigralbus, i think a creature with more than one head could, but not a creature with just one, because the flanking is caused for the creature's difficulty to track many different foes at the same time. \$\endgroup\$
    – cablop
    Commented Jan 27, 2016 at 18:15
  • \$\begingroup\$ @Theik, i think size is really relevant. In fiction small creatures use to flank bigger ones, gnomes flanking humans, humans flanking hill giants, dwarfs flanking dragons. The problem in the question is... faeries tend to flank humanoids but the rules don't account for it, because faeries have no reach! o.O \$\endgroup\$
    – cablop
    Commented Jan 27, 2016 at 18:17

The problem is that the square that a creature occupies is not only tied to its space and reach, but also actions, speed and time.

Squares are used in the game with the idea that this is the space a creature requires for the actions it performs during one round. The creature could be at any place of that square during those actions: the center, a border, a corner, etc. This is why facing rules are not in use in PF: because a creature is constantly moving during combat, even when not moving to other squares - except when flat-footed, and even in that case it can be moving its head and eyes. To make an idea of it, compare the battle situation with a game like basketball or soccer; people is really aware of what's happening around in every 6 seconds span.

With Tiny or smaller creatures that means many small creatures sharing the same square are at any place of the square during their actions - so they're flanked - and the next second, a fraction of a round, they're not. In practice, a Tiny or smaller creature can move to a place in the same square where the other creatures occupying the same square cannot flank it.

The thing becomes a mess when you mix a Medium or Small creature with Tiny or smaller creatures; the Tiny creatures could effectively flank, because the Small/Medium creature actually cannot keep an eye on them but the rules don't account that fact.

I like Zimul8r's answer, specially this: "to correct this problem, I'd try a house rule that says that if you're sharing a square with another creature you need to declare which adjacent square you're closest to, i.e. who's on what side of whom in the square. Then you can use the positioning rules with respect to that creature specifically, like flanking, as though you were in the adjacent square", but I would make it a (homebrew) feat for Tiny and smaller creatures rather than an alternative (homebrew) rule for everyone or any size. To keep things simple it won't apply if the defender is also a Tiny or smaller creature. In fact, even allowing it, the defender just needs to select the same adjacent side as one of the attackers is selecting and cannot be flanked by them. Maybe you can create that (homebrew) feat and, a la rogue/barbarian, only tiny or smaller creatures can be flanked by tiny or smaller creatures 4 levels (or HD) higher - and having the feat, of course.

To split the square in smaller squares don't work, because if you do that you are automatically making the tiny or smaller creatures slower than what the rules account for them. And in real life and game rules the situation is the opposed, smaller creatures are faster than bigger creatures in relation of their sizes. To make yourself an idea, compare two elephants engaged in battle to two cats engaged in battle. The first ones are slow to switch positions while if you blink too much you miss when the cats switched sides (even inside the same 5ft square). Now add an elephant and a cat to the mixture (accordingly); while it's clear that two elephants can easily keep another flanked in a 6 seconds span, cats can't, it is hard for them to keep the other cat in between for 6 seconds inside a 5ft square. If you split the grid, you'll need to split the 6 seconds too, and then you are in a mess because you cannot split move and standard actions.

  • \$\begingroup\$ Welcome to RPG.SE. I see that you are already an SE member on other sites. Please take the tour to see how our SE works. The edit was intended to improve flow. If any meaning was lost, use the edit function to correct any error I may have made. \$\endgroup\$ Commented Jan 2, 2016 at 17:06

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .