I’ve heard this phrase being thrown around sometimes on other game tables. Apparently, it describes a straight line of melee combatants on a grid, alternating between members of two opposing groups. This only occurs if the Flanking Variant Rule are used. Under these circumstances, the Conga Line of Death makes sense from a mechanical standpoint, as every melee combatant wants to get advantage on their attack rolls. If this rule were in place, player characters as well as NPCs would understand the in-universe ramifications and probably try to get into a superior position every time, leading to the aforementioned Conga Line of Death.

Now my question is: How can I, as DM, avoid the Conga Line of Death occurring when implementing some form of flanking rule?

The obvious answer would be: “Don’t use the Flanking Variant Rule”. Well, I for one like to grant some form of advantage, when two combatants gang up on their opponent. And it kind of makes sense, that it is easier to hit somebody who has to avoid the attacks of two enemies. So I want to keep Flanking in my game, but like to prevent the Conga Line of Death.

Negation of Advantage

At our table we use the Variant Flanking rules, however we noticed the same problem as yourself, and added the corollary that you cannot gain Advantage from a Flank if you yourself are being Flanked. The thematic justification was that you are busy trying to cover your own back and can't put all of your attention onto exploiting the enemy's defensive gaps.

This is justified mechanically under the rules for gaining advantage and disadvantage:

The GM can also decide that circumstances influence a roll in one direction or the other and grant Advantage or impose Disadvantage as a result.

It led to players holding formations, covering each others back and using the terrain more to their advantage, using low walls and pillars to block enemy movement into the now more limited flanking positions.

We have not experienced the conga line, it may not be as a big of a concern as you think

My tables have used the flanking rules on a grid for about 5 years and we're a heavily combat focused group - and I don't think we've ever gotten in a congo line. This may be a mix of our own playstyle just not wanting to conga line, but I think it's also in how we approach combat.

But why? That's one is a better harder to parse, but I think it's for a few reasons:

1. Grouping together leads to possible Fireball Formations (everyone being caught in an Area Effect if cast)


2. Enemies are a mix of melee and ranged attacks that forces the group to work together across the map


3. Enemies have often come in waves which also forces us to be prepared. Keeping everyone centralized or in a line does not put us in a defensible position to cover each other.

The above are possible reasons why we haven't experienced it which makes me think maybe this isn't as much of a problem as you think it may be.

As a DM, you should be considering tactics. As players, we are aware of and concerned about Area Effect spells (including things that travel along a straight line) and if this tactic starts to become overused, you can counter with those types of spells and using creatures with resistance/immunity to the associated damage types to let your players know that this choice may not be the safest.

Given the above, I wouldn't make any changes/do anything different until you actually see a problem occurring at your table.

But utilizing some of the things I've noticed about our encounter designs may help reduce the odds if you do start to see your players lining up for you :)

Flanking does present another issue: More advantage triggered mechanics

The most 'problematic' thing I've seen with flanking is that minimizes the difficulty of getting advantage for many abilities that trigger off of that mechanic. It's much easier to get, which means those abilities trigger much more often (and other abilities become unnecessary because it's relatively easy to flank compared to the other advantage giving mechanics.)

Help!

Our table uses the Help action (use your action to grant advantage to an ally) to do this. If you use this instead of the capital-F Flanking rules to represent better manpower resulting in advantages, it does mean someone’s going to have to spend their action not attacking and this isn’t quite as powerful (for players or enemies), but it still allows the gang-up effect you’re wanting to preserve and, being usable from anywhere around the enemy, eliminates the Conga Line of Death.

So far at our table, it’s resulted in battle lines rather than conga lines, even with a rogue in the party.

Noah Antwiler has a video about the Conga Line of Death. At ~29:52 into the video, he suggests using group initiative to prevent the Conga Line of Death forming in a combat encounter.

Although I haven't tried this rule, the Side Initiative option (page 270 in the 5e DMG) allows players to use group initiative. Since players & monsters are moving as a group rather than one by one, combatants would be encouraged to maintain a solid rank (shoulder to shoulder) to avoid being flanked.