Last Updated on January 22, 2023
For some players and DMs of DnD 5e, combat should be more tactical. These players may be interested in DnD’s optional flanking rule which makes positioning more important.
This guide will explain the mechanics of this optional rule, what kinds of benefits and drawbacks using it has, and how best to use it to your advantage whether you’re a DM or a player.
What is Flanking?
In DnD 5e, flanking is an optional rule meant to represent the combat advantage you gain when you and your allies attack an enemy from multiple directions.
In a real-life situation, this would mean your opponent would be off-balance, distracted, and unable to properly defend themselves, a situation that would only get worse the longer the fight went on.
Of course, in DnD it’s difficult to mechanically represent distraction or being off-balanced, so 5e simply grants advantage to flanking players.
Earlier editions, like 3.5, gave flanking players a +2 bonus to their attack rolls. However, many of these kinds of circumstantial bonuses have been replaced by the simpler and easier to keep track of advantage/disadvantage system.
There are several restrictions to how flanking works in 5e, and who can benefit from it. While the basic rules don’t contain information on this optional rule, information about it can be found in the Dungeon Master’s Guide on page 251. We’ll quote the rules here since flanking can be a little confusing in some situations.
Basic Flanking Rules
This is what the Dungeon Master’s Guide says about flanking:
“If you regularly use miniatures, flanking gives combatants a simple way to gain advantage on attack rolls against a common enemy.
A creature can’t flank an enemy it can’t see. A creature also can’t flank while it is incapacitated. A Large or larger creature is flanking as long as at least one square or hex of its space qualifies for flanking.
When a creature and at least one of its allies are adjacent to an enemy and on opposite sides of the enemy’s space, they flank that enemy, and each of them has advantage on attack rolls against that enemy.”
There are a few important takeaways from these rules. Flanking only works if you are using battle maps to keep precise track of enemy position. While theatre-of-the-mind combat is a great way to play DnD, it won’t work for this rule.
This is probably because it would be too easy for disputes to arise about who is and who is not flanking.
You also can’t flank if you can’t see your enemy or you’re incapacitated. That means you have to be actively a part of the combat, though you don’t have to be throwing punches or brandishing an axe to participate! That means that familiars, who can’t attack, can create a flanking situation.
Importantly, flanking only works when creatures are adjacent to an enemy. Adjacent creatures are within 5 feet of each other, and occupy squares (or hexes) that share a border on a battle map. Remember that this is not the same as melee range, as some weapons and abilities will grant an increased melee range.
A soldier with a spear can make attacks against a goblin 10 ft away, but they cannot benefit from flanking unless they move closer.
Now that we’ve covered the basic idea, let’s look at how flanking actually works on square and hex grids.
Flanking on Hexes
Here’s how the Dungeon Master’s Guide describes flanking on Hexes:
On hexes, count around the enemy from one creature to its ally. Against a Medium or smaller creature, the allies flank if there are 2 hexes between them.
Against a Large creature, the allies flank if there are 4 hexes between them. Against a Huge creature, they must have 5 hexes between them. Against a Gargantuan creature, they must have at least 6 hexes between them.
The Dungeon Master’s Guide provides an example image of how one should count hexes to determine flanking, seen below.
In this image, a Large creature is being flanked by two Medium creatures, as shown by the four hexes between the two creatures. It’s worth noting that multiple creatures can benefit from flanking using precise positioning.
A third ally, adjacent to either of the first two and to the Large creature being flanked would also be able to benefit from flanking. There would be enough hexes between them and the opposing ally, though you would need to count in the other direction.
However, a third ally that was adjacent to the creature being flanked, but not adjacent to any of the first two allies would not benefit from flanking, according to rules as written. There would be a maximum of one, not four hexes between allies in that case.
Flanking on a Square Grid
Square grid flanking works similarly to hex flanking, though it is easier to figure out. Flanking creatures must simply be on opposite sides or corners of the flanked creature’s space.
When in doubt about whether two creatures flank an enemy on a grid, trace an imaginary line between the centers of the creatures’ spaces. If the line passesthrough opposite sides or corners of the enemy’s space, the enemy is flanked.
Below is a simple diagram generated in Roll 20 that demonstrates this with a Large enemy and two Medium allies.
These two knights are successfully flanking the Large orc.
These two knights are also successfully flanking.
However, these knights are not flanking, as they are not on opposite sides or corners of the orc.
Controversy around Flanking
Flanking is often considered a controversial optional rule, so it’s always good to check with your DM before assuming it’s in effect. Many people don’t like the flanking rule either because it supports silly gameplay or because they believe it’s overpowered.
The Flanking Conga Line
Some players worry that instituting flanking too often results in ‘conga lines’ of enemies and players, such as in the following diagram, generated in Roll20.
Here a series of soldiers and goblins have all lined up in order to benefit from flanking, rather than fighting in a way that makes sense.
Putting aside the silliness of having combat encounters devolve into lines of alternating enemies and allies, many players and DMs worry that this sort of tactic makes combat uninteresting and takes away the importance of positioning in favor of meta-gaming every bonus you can get.
Personally, I don’t see the conga line as an issue, though I admit it can and has happened.
This sort of combat can only happen with active participation from the DM, corralling the enemies into falling into this pattern.
There are lots of ways to keep the flanking rules without falling into conga-line silliness. For example, not all enemies might be aware enough or social enough to pursue flanking positions.
Moreover many combatants, players and enemies both, will be primarily ranged damage dealers or even magic users that can’t stand up to melee combat. These characters won’t benefit from flanking, and this kind of scenario might even impede their ability to get a clean shot. A conga-line only really even begins to make sense in a pure melee martial combat scene.
Even then, lining up like this comes with its own penalties. A smart group of enemies might realize they could simply all team up against a single enemy for one round, downing them, and making the entire fight a lot easier for their side.
Above, the 4 goblins could take a few opportunity attacks to get into a double flanking position around the soldier on the right in a single round. Advantage is nice, but it isn’t as good as knocking out an opponent.
The conga-line isn’t actually the most advantageous RAW way to engage in combat, and as you’ll see later there are many ways to make flanking a group of enemies either much harder or impossible. It’s a silly idea, but there’s little reason for it to be unavoidable in actual play.
Flanking is Overpowered
The other worry about flanking is that it provides a relatively cheap way to get advantage on attacks. Compared to Greater Invisibility, which grants advantage against most (but not all) creatures for 1 minute and costs a 4th level spell slot, flanking only requires an ally and nothing else.
There is merit to this idea, but it’s important to remember that flanking isn’t unbeatable. A good flank may only last a single round before the enemy simply moves out of its compromised position, and Greater Invisibility offers many other useful traits. It’s much harder to target invisible creatures with spells, for example.
Flanking is also great for unlevelled NPCs. While flanking may be a cheap way to gain access to advantage for players, it’s often the only option available for the town guard. Flanking is thus one of the few tactical options available to NPCs without spells or special abilities.
Sometimes DMs might consider adding a homebrew rule which gives flanking creatures a +2 bonus to their attack roll instead of advantage, like in DnD 3.5.
This is to provide some benefit for flanking, but not something as powerful as advantage, which can provide effectively about a +3 or +4 bonus on average, depending on how high a roll you need (see this page for more details about the benefits of advantage).
However, this ignores the fact that advantage doesn’t stack. If you have advantage on a roll, you can’t get “double advantage”. There’s little benefit to flanking an enemy as well as gaining advantage some other way.
Plus, DnD 5e’s approach to attack rolls means that a +2 bonus that can potentially stack with another source of advantage is actually much more useful and much stronger than advantage by itself.
DnD 5e uses “bounded accuracy”. By design the game tries to avoid extremely high ACs and attack bonuses. The non-stacking nature of advantage is actually crucial to the game’s intended balance, designed to prevent creating situations where a player has an extremely high chance to hit.
Adding house rules is fine, but if you’re trying to make flanking less beneficial, letting it give a small flat bonus actually makes it more powerful, not less. Of course, if you want to make flanking more powerful, go for it!
How To Use Flanking Effectively
In combat between two groups, both groups will be trying to flank the other while preventing themselves from being flanked.
This means that in groups aware of flanking, members will be careful not to overextend themselves. That might mean becoming isolated, an easy pickings either for enemy flanking moves or enemy ranged attackers who now have a clear shot at you.
In smaller encounters, ranged characters can also benefit from flanking. Although ranged attacks made from within 5 feet of your target suffer disadvantage, this is cancelled out due by the advantage from flanking. Consider taking advantage of this when your archer character finds herself in melee.
Downsides to Flanking
It’s not always a good idea to flank. Consider this party of two archers and two soldiers meeting 4 orcs in a hallway.
It seems that the orcs have left themselves open to being flanked by the soldiers. However, if they try to flank the lead orc in an attempt to knock him out of the fight before dealing with the other enemies, they leave their squishier archers undefended.
As you can see, the two orcs to the right will probably be quickly killed by the soldiers, but at the cost of letting the archers also get knocked out. Even if the party wins this fight they’ll take more damage than they need to. In the worst case scenario, the soldiers will be left surrounded themselves after the archers have been finished off.
As you can see, you should be careful about when you try to flank your enemies. In some scenarios you risk overextending and exposing your squishier allies.
How to Stop Being Flanked
The best way to prevent yourself from being flanked is to prevent enemies from getting behind you. The following diagram, generated in Roll20, shows a group of trained soldiers taking on some orcs.
Because of their half-circle formation (a full circle also works), no orcs can get to an opposite square of any of the soldiers. As a result, the soldiers are able to deny flanking benefits to their enemies, a key skill if they happen to be outnumbered (just imagine more orcs off screen).
Common Questions About Flanking in DnD 5e
Does flanking give sneak attack 5e?
If you are benefitting from flanking you gain advantage, which is sufficient to trigger the sneak attack feature of the Rogue as long as you are using a melee weapon, since ranged attacks do not benefit from flanking.
If you are using a ranged weapon, keep in mind that since an ally that is not incapacitated is within 5 feet of your enemy you can still activate your sneak attack feature as long as you don’t have disadvantage.
Does prone give flanking?
If an enemy is prone, you can still flank them. However, since the prone condition grants advantage on all melee attacks within 5 feet, you will already have advantage on your melee attacks. Advantage does not stack.
Can spells flank 5e?
Spells that use an attack roll can benefit from flanking in 5e. However, spells that do not specify a melee attack roll are considered to be ranged spell attacks, and therefore, as ranged attacks against adjacent targets, suffer disadvantage.
This means that ranged spell attacks that benefit from flanking get a normal roll, as advantage and disadvantage cancel out, while melee spell attacks that benefit from flanking can be rolled with advantage.
Does Spiritual Weapon get flanking 5e?
Spiritual Weapon is a Cleric spell that conjures a floating weapon. The weapon itself is not an ally, and so its presence adjacent to an enemy can never trigger flanking.
However, if you are flanking an enemy, the melee spell attack roll you make to hit with the floating weapon against the enemy you are flanking does have advantage, even if the weapon is in a different place around the enemy than you are.
Should you use Flanking?
Personally, I think flanking is a great rule for DnD 5e. It offers additional tactical options for players and helps DMs develop combat tactics for enemies who don’t have magic spells and supernatural abilities backing them up.
While it isn’t always the best idea to try to pursue flanking, the existence of the rule can lead to more tactical gameplay and making better use of your party’s abilities.
This simple method for gaining advantage can have far reaching consequences for how you run combat, and how player’s choices and movement can shape the success or failure of encounters.
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Growing up I spent most of my time reading, so when I first started playing RPGs in middle school and got a copy of DnD 3.5’s rules I loved their collaborative take on storytelling. These days I like to use RPGs to develop my creative problem-solving skills as well.