Is Flanking in D&D a Good Optional Rule for Your Table?

Flanking is an optional rule in Dungeons & Dragons 5e that can add a layer of strategy to your combat encounters. While it gives players (and monsters) more options in combat, it’s not for every table. I personally don’t use flanking in my games, but whether or not you should introduce flanking into your game depends on your playstyle and the type of challenges you want to present to your players. Here’s an overview of how flanking works, when to use it, and some pros and cons to help you decide if it’s a good fit for your table.

Flanking in 5e: The Basics

Flanking in Dungeons & Dragons 5e is an optional rule presented in the Dungeon Master’s Guide that allows players to gain a strategic advantage in combat scenarios. It’s a tactical maneuver that can be used when two allies are positioned on opposite sides of an enemy.

According to the rule, which can be found in Chapter 8 of the DMG, when a creature and at least one of its allies are adjacent to an enemy and on opposite sides or corners of the enemy’s space, they are said to be flanking the enemy. When flanking, each of the allies gains Advantage on melee attack rolls against that enemy. 

However, it’s important to note that flanking is an optional rule, and the decision to use flanking in a game is entirely up to the Dungeon Master (DM). Some DMs might choose not to use it because it can overly complicate combat or make encounters too easy for the players. Others might choose to use it to add an extra layer of strategy and positioning to their combat encounters.

Flanking With a Grid

As it adds more tactics, strategy, and housekeeping to combat, flanking is most often used by groups playing with a battle map or virtual tabletop of some sort. 

For a creature to be considered flanking, it must be adjacent to the enemy and on the opposite side or corner of the enemy’s space, along with at least one of its allies. This applies to both square and hexagonal grids. In cases of uncertainty on a grid, an imaginary line drawn between the centers of the creatures’ spaces can help determine if the enemy is flanked. If the line crosses through opposite sides or corners of the enemy’s space, the enemy is considered flanked.

On hexagonal grids, the number of hexes between the allies determines if they are flanking a Medium, Large, Huge, or Gargantuan creature. For Medium or smaller creatures, there should be 2 hexes between the allies. For Large creatures, there should be 4 hexes, for Huge creatures, 5 hexes, and for Gargantuan creatures, at least 6 hexes.

Flanking With Theatre of the Mind

Flanking can also be utilized in “Theatre of the Mind” style play, where combat and scenarios are described verbally without the use of a physical map or miniatures. However, it can be a bit more challenging to implement due to the abstract nature of positioning in this style of play.

In Theatre of the Mind combat, players would need to clearly state their intent to position themselves in a way that would allow for flanking. For example, a player might say, “I want to move around the ogre, to attack it from the opposite side as my ally.” It would then be up to the players and the DM to remember this information so the necessary bonuses can be applied.

The Pros: When Flanking Can Improve Combat

• Increased Tactical Depth: Flanking encourages players to think about positioning and to discuss strategy with their party, rather than just charging in. The ability to gain Advantage on attack rolls adds is very tempting for martial characters, especially when dealing with tough enemies with high AC.
• Helps Close the Marital/Caster Divide: I am firmly in the camp that martials are at an innate disadvantage to their caster counterparts. Flanking allows them to hit more reliably, increase DPR. But, it is a double-edged sword because enemies can also flank them.
• It Works Well on Maps or VTTs: Flanking is most effective when using a grid-based battle map or virtual tabletop (VTT).  Whether using squares or hexes, a grid makes it easier for players to understand where they need to be in order to flank and gain the Advantage.

The Cons: When Flanking Might Not Be Ideal

• Increased Complexity: The single biggest drawback of flanking is that it can add complexity to combat, especially for DMs and players who prefer a faster, more fluid style of play. Keeping track of which enemies are flanked and remembering to apply the Advantage can slow down your turn. If your group prefers a quick and simple combat experience, flanking may feel like an unnecessary complication.
• Hard to Implement Without a Grid: For groups that prefer Theatre of the Mind play, flanking can be difficult to manage, to the point where I would say you shouldn’t bother with it. Without a physical map or visual reference, it puts a lot of work on the DM’s plate, which is unideal because they already handle so much.
• Your Character’s Don’t Have Mobility Builds: This is a niche con, but a con I have experienced nonetheless. In D&D combat, I find players rarely want to be on the receiving end of Opportunity Attacks, nor do they want to waste an action to Disengage. If you try to flank them with monsters, it might result in a static “congo line” of flanking, which I find breaks immersion.

Flank the Tank

Flanking is a tactical aspect of D&D 5e that can turn the tide of a battle. Understanding the rules of flanking and how to use it effectively can make your combat encounters more dynamic and strategic. Hopefully, now that you’ve learned how advantageous flanking can be, you’ll incorporate it into your combat strategy!