So I wanted to share with you a few ways a competing fantasy RPG - 13th Age - handles "theater of the mind" that you could house-rule into your 5e games. 13th Age is not some fan created hack (no offense to all the awesome fan hacks out there). It was written by Rob Heinsoo and Jonathan Tweet, lead designers of 4th and 3rd edition D&D, and published by Pelgrane Press, an experienced, thriving game company with a vast library of ENnie award-winning titles, including 13th Age (which took silver for Best Rules in 2014).
Before we start, you should be aware that 13th Age has an SRD, so everything I'm talking about is publicly available at www.13thagesrd.com. I recommend if you like what you read, that you go buy the 13th Age core book, because the art is phenomenal (you don't get that from the SRD!) and the game is great. I like Pelgrane so much I just linked their page directly instead of using my amazon affiliate link (not that those ever generate any income, but it's the principle of the thing.) Also, the Theater of the Mind combat rules are only one of 13th Age's interesting and innovative mechanics. Go check it out!
On to the meat of the article. The four things you need to consider with theater of the mind tactical combat are...
- Range and Movement
- Positioning, Tanking, and Intercepting
- Area of Effect Magic
This is an article for 5th Edition D&D DMs struggling with Theater of the Mind action. So I'm going to cover how 13th Age handles these four things, and give you a tip after each that will help you improve your 5th Edition D&D game by importing some wisdom from 13th Age.
Range and Movement
There are three ranges in 13th Age: Engaged (you're right next to them), Nearby (you can get to them in one move), and Far Away (two moves away from enemies, possibly more). Ranged weapons fall into three categories. Some can only hit Nearby enemies (thrown dagger), some can hit Nearby enemies and also Far Away enemies at -2 (javelin), and some can hit Nearby and Far Away enemies equally well (bows and crossbows).
13th age doesn't measure movement down to increments of five feet. It's designed explicitly for Theater of the Mind action (though many 13th Age groups still use minis and maps), so it cares about where people are relative to each other instead of exact distances. They make a few sacrifices for this: Halflings and Dwarves can move around in combat as quickly as Elves and Humans. But on the other hand, there's no need to get into arguments about distance, track who's within 30' for your javelin, and quarrel about whether your cleric can move to the fallen ranger to heal them. The distance between things is measured in moves, not feet.
In 13th Age, a character can move to anything that's Nearby with their move. A character can close distance from Far Away from something to Nearby with their move. A character can Disengage with a move. Disengaging is different from 5e D&D. In 5e D&D, Disengage is an action. In 13th Age, it's a move. You either move away and take an opportunity attack or make a roll to Disengage (like the old 3rd edition Tumble check). If you fail, you lose your move. Some classes get abilities that interact with the Disengage roll to make them good at hit-and-run tactics. I actually like the 5th edition D&D Disengage rule better than the 13th Age rule (5e also gives classes Disengage mechanics - see the Rogue's Cunning Action).
5e DM Tip! If you're using theater of the mind action, it's already impossible to tell whether a Dwarf is too slow to get to a nearby enemy, unless you constantly track relative distances between each and every character in the scene. Nobody does that. So start describing distance in terms of "moves" instead of feet, with the understanding that one "move" is about 25 or 30 feet, if it matters.
Positioning, Tanking, and Intercepting
When you're using minis and a battlemap, the tactical movement options in 5e are wide open, but when you're using Theater of the Mind, it's impossible to keep track of the exact distance, in feet, between your character and every other relevant character and object in the encounter. So your options for tactical positioning in 13th Age are not limited just because there's no grid. They added a positioning system that doesn't use feet, but allows you to make declarations about where you are relative to other combatants. That means you can keep track of a lot more information about relative positions since it's not all in exact numbers of feet. There's no trigonometry involved. Here are some of your positioning options in 13th Age:
You can move Far Away to avoid being attacked. Since that takes two moves, nothing can both move to you and attack, and some ranged weapons can't hit you.
You can move Behind an ally, forcing enemies to go around the ally to get to you. Any time an enemy tries to go around you, you can Intercept them, which lets you become Engaged with them and end their movement.
When you're Engaged with an enemy, it's hard for them to get away. So you can "tank" by engaging with enemies. They have to make a check to move away from you without taking an opportunity attack, and if they fail, they lose their move; or they can decide to just move away and take the attack without trying to disengage. Protector type classes (and monsters!) have abilities that interact with the intercept, disengage, and opportunity attack mechanics to make them more "sticky." Skirmisher type classes (and monsters!) have abilities that interact with these mechanics to make them more "slippery."
Other situations that are less clear are resolved with a GM call or an ability check if there's disagreement. So if you rush the necromancer, and the GM says you have to go around his zombies to do it, the GM might refer to when they described the scene "I said the zombies filled the hallway shoulder to shoulder, with the necromancer behind them." You can counter by saying "Yeah, but I can try leaping off the altar and swinging from the hanging tapestry, up out of their reach," and the GM will call for a Dex check.
5e DM Tip! You can't copy 13th Age positioning into D&D without a lot of house rules, but you can take its advice about "Dicey Moves" -- any time a player argues that they can make a move in theater of the mind action, and you disagree, instead settle the disagreement with a die roll. This is part of the larger "say yes or roll the dice" principle. Any time a player wants to do something, and you think the opposition is too great, it's a disagreement over whether their character is good enough to overcome it. That's literally what the system is for: Let the dice decide whether their character is good enough.
Area of Effect Magic
5th edition D&D handles area of effect magic all wrong for theater of the mind. It tells you that your character can send a streak of flame from your character's fingertip to a point you choose within 150' assuming your character has uninterrupted line of effect to that spot, at which point it explodes into a 20' radius sphere centered on that point, spreading around corners. To know if you can hit multiple creatures, you need to know how far they are from you, how far they are from each other, how far they are from your allies, and then compute some trigonometry to figure out if you can choose a point to target that will hit as many enemies as possible without hitting your allies. That's totally inappropriate for theater of the mind, and it results in a lot of "Haha sucker! You also hit the fighter! Ragnar has to make a Dex save!"
Take a look!
Casting Time: 1 action
Range: 150 feet
Components: V, S, M (a tiny ball of bat guano and sulfur)
A bright streak flashes from your pointing finger to a point you choose within range and then blossoms with a low roar into an explosion of flame. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 fire damage on a failed save, or half as much damage on a successful one.
The fire spreads around corners. It ignites flammable objects in the area that aren’t being worn or carried.
At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.
13th Age is better for theater of the mind play. It says that at any given time there are 1, 2, or 3 enemies close enough together that you can hit them, and if you're willing to cast it recklessly (which is a no brainer if your allies are not currently engaged with the enemy), you can actually get 2-6 enemies inside its explosive radius. Instead of the GM deciding if you can hit 1 or 3 enemies, you roll a die.
Ranged spell; Daily
Special: When you cast this spell, you can choose to cast it recklessly.
Target: 1d3 nearby enemies in a group. If you cast recklessly, you can target 1d3 additional enemies, but then your allies engaged with the target may also take damage (see below).
Attack: Intelligence + Level vs. PD
Hit: 10d10 fire damage.
Miss: Half damage.
Reckless miss: Your allies engaged with the target take one-fourth damage.
7th level spell 12d10 damage.
9th level spell 20d10 damage.
Champion Feat Casting the spell recklessly increases the number of additional targets to 1d4 instead of 1d3.
Epic Feat Increase the number of targets to 1d3 + 1 instead of 1d3.
DM Tip! 5th edition D&D doesn't have such elegant theater of the mind AOE rules. So you have to accept player assertions, like "I can get the three skeletons fighting Ragnar without hitting him." If you start quibbling these things, you're wasting time and setting up an adversarial relationship with the players.
It doesn't get more high stakes than a battle you're about to lose. And when the stakes are high, whether or not you can successfully retreat and save your hide is a big deal. In a game where distances and movement and relative positioning are measured in feet, it's a mess.
If you're routed in 5th edition D&D and decide to retreat, the combat system is not your friend. Movement speeds in feet, initiative rounds, etc. all stack up against you, even if you're using a grid and miniatures. Running away from a fight should not be that hard.
In 13th Age, it's much easier: "Fleeing is a party action. On any PC's turn, any player can propose that all the characters flee the fight. If all players agree, they successfully retreat, carrying any fallen heroes away with them. The party suffers a campaign loss. The point of this rule is to encourage daring attacks and to make retreating interesting on the level of story rather than tactics." (http://www.13thagesrd.com/combat-rules)
A "campaign loss" means "something bad happens in the story because you were defeated." It doesn't mean you "lose the game." Obviously, that's better than a TPK. Because retreating is easy to understand and easy to do, players in 13th Age are braver and GMs can create more deadly situations without worrying about causing a TPK -- and as a result, the PCs lose more fights, but the campaign doesn't grind to a halt.
5e DM tip! Import the 13th Age "Flee" rule wholecloth. It'll make your PCs take bigger risks, and they'll lose more fights without ending the campaign. It's a win-win!