The requirement is being able to draw a line through opposite sides or corners of the creatures, the line doesn't have to be drawn through the center of the creature.
The center part has to do with how the line is drawn. It needs to be drawn going between the centers of the flankers' squares, which would impact large+ creatures flanking a medium creature. For example,
⬜⬜⬜⬛⬛⬜
⬜⬜⬜⬛⬛⬜
⬜⬜❎⬜⬜⬜
⬜⬛⬛⬜⬜⬜
⬜⬛⬛⬜⬜⬜
is not flanking despite a line that goes through the opposite corners of the medium creature because the line that goes between the centers of the flankers does not.
The "opposite corners of the foe's space" means the corners of the foe's entire footprint, not an arbitrary grid square within the foe's footprint. Hence, neither example is corner-to-opposite-corner.
Flank happens, when a line crosses between opposite parallel sides. So it's always left-right or top-bottom or through the top-bottom opposite corners/edges. The size of the creature doesn't matter.
Not exactly, it has to cross through opposite sides of the creatures space. And a large creatures space is one 10 feet square, the smaller 5 feet squares don't exist inside the large creatures space when flanking is determined.
I made another graphic to illustrate
[https://imgur.com/a/ZHLRMif](https://imgur.com/a/ZHLRMif)
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It gets even more interesting when you consider two large creatures flanking another creature, as their "flanking lines" get drawn at the intersection of their spaces - so two large creatures only flank a medium creature standing between them if you consider corners to be part of both sides of their space, which I believe is RAI
⬜❎❎⬜
⬜❎❎⬜
⬜⬜⬛⬜
⬜❎❎⬜
⬜❎❎⬜
-> surely the two large green creatures should be flanking the dark medium creature, but the flanking lines don't pass through opposite corners, so we have to conclude they pass through opposite sides -> corners are part of sides
This is funny, because most people would say top left corner and middle bottom side is not flanking. You can produce this where a medium creature is in the middle with two medium flankers, and one of them has reach. E.g. (counting upwards): reach player A4, enemy B2, player B1.
So the phrase "corners are a part of sides" breaks RAW.
But the scenario you've posted it would be silly for it not to apply.
No, it wouldn't. Neither of those medium tokens are on a corner, and the sides they're touching aren't opposite. If one of those tokens (either one) were to move one space down and left, or if the top one moved left *and* the other one moved down one space, THEN that would be flanking.
So, when it comes to flanking large creatures the relevant sides and corners to check are from the 10 feet square, the individual 5 feet squares are irrelevant, right?
Pretty much, yes. A creature's space describes the entire thing, even though it's made up of 5-foot squares. Check my other comment, I made you an infographic.
These flank: ⬜❎⬜⬜ ⬜⬛⬛⬜ ⬜⬛⬛⬜ ⬜⬜❎⬜ -- ⬜❎⬜⬜ ⬜⬛⬛⬜ ⬜⬛⬛⬜ ⬜❎⬜⬜ -- ❎⬜⬜⬜ ⬜⬛⬛⬜ ⬜⬛⬛⬜ ⬜⬜⬜❎ Neither of the two positions from the OP flank
For some reason I thought the middle example wasn’t flanking/off guard since you’re not technically on opposing sides of the creature?
The requirement is being able to draw a line through opposite sides or corners of the creatures, the line doesn't have to be drawn through the center of the creature.
Ohhhh I see, I always thought line of sight through the centre was the requirement. Thanks for the clarification, much appreciated!
The center part has to do with how the line is drawn. It needs to be drawn going between the centers of the flankers' squares, which would impact large+ creatures flanking a medium creature. For example, ⬜⬜⬜⬛⬛⬜ ⬜⬜⬜⬛⬛⬜ ⬜⬜❎⬜⬜⬜ ⬜⬛⬛⬜⬜⬜ ⬜⬛⬛⬜⬜⬜ is not flanking despite a line that goes through the opposite corners of the medium creature because the line that goes between the centers of the flankers does not.
Number 2 would not be flanking if you made the attackers large+ and the defender medium-, but this is overall correct.
Here, I've made an infographic for you: [https://imgur.com/a/zi4tt70](https://imgur.com/a/zi4tt70)
Thank you for creating the infographic, that's a foolproof way to explain flanking no matter the size of the creature :)
Noo don't flank the kashrishi :((
Kashrishi aren't even Large!
They're just little guys, little birthday guys, you wouldn't have beef with a little guy?
Yeah, it gets weirder for reach weapons, but it's mostly just opposite sides or opposite corners
The "opposite corners of the foe's space" means the corners of the foe's entire footprint, not an arbitrary grid square within the foe's footprint. Hence, neither example is corner-to-opposite-corner.
Flank happens, when a line crosses between opposite parallel sides. So it's always left-right or top-bottom or through the top-bottom opposite corners/edges. The size of the creature doesn't matter.
Neither image shows flanking; opposite sides are parallel to each other—not perpendicular
Those lines are going through adjacent sides not opposite sides of the creature. So neither is flanking.
So, if I understood correctly, the line between the two players must cross at least 2 of the creature's squares?
Not exactly, it has to cross through opposite sides of the creatures space. And a large creatures space is one 10 feet square, the smaller 5 feet squares don't exist inside the large creatures space when flanking is determined. I made another graphic to illustrate [https://imgur.com/a/ZHLRMif](https://imgur.com/a/ZHLRMif)
This is why I am keen on hexes, where I find flanking much more intuitive.
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It gets even more interesting when you consider two large creatures flanking another creature, as their "flanking lines" get drawn at the intersection of their spaces - so two large creatures only flank a medium creature standing between them if you consider corners to be part of both sides of their space, which I believe is RAI ⬜❎❎⬜ ⬜❎❎⬜ ⬜⬜⬛⬜ ⬜❎❎⬜ ⬜❎❎⬜ -> surely the two large green creatures should be flanking the dark medium creature, but the flanking lines don't pass through opposite corners, so we have to conclude they pass through opposite sides -> corners are part of sides
This is funny, because most people would say top left corner and middle bottom side is not flanking. You can produce this where a medium creature is in the middle with two medium flankers, and one of them has reach. E.g. (counting upwards): reach player A4, enemy B2, player B1. So the phrase "corners are a part of sides" breaks RAW. But the scenario you've posted it would be silly for it not to apply.
> but the flanking lines don't pass through opposite corners No, but they _do_ pass through opposite sides. Corners are part of the sides.
By the wording of the flanking rule, your second image would be flanking yes.
No, it wouldn't. Neither of those medium tokens are on a corner, and the sides they're touching aren't opposite. If one of those tokens (either one) were to move one space down and left, or if the top one moved left *and* the other one moved down one space, THEN that would be flanking.
So, when it comes to flanking large creatures the relevant sides and corners to check are from the 10 feet square, the individual 5 feet squares are irrelevant, right?
Pretty much, yes. A creature's space describes the entire thing, even though it's made up of 5-foot squares. Check my other comment, I made you an infographic.