D&D General An Algorithm for DMs in Combat


Hi everyone.

I've been wanting to make a loose algorithm for DMs to reference in combat for guiding actions of monsters and NPCs. I've been running games for 22 years now, but even I could use some guidance and a tool to offload mental energy onto.

I've played a few D&D style boardgames that have no GMs and instead have rules for how the monsters behave on their turn. I've also played plenty of tactical RPGs where enemy behavior is reasonably predictable (attack closest enemy, attack lowest armor in range, etc). These have made those games "easier" to play, because the players have more predictive power to prepare for upcoming rounds.

So, I was wondering what you think a system would need. My thoughts was to make guidance for different encounter types, using the 4E D&D encounter types. For instance, they had a hit and run encounter where the enemies are all skirmishers, more mobile but otherwise average enemies; half engage in melee while the other half stay ranged, and then they switch when the meleers gets injured.

I'd want to keep this relatively simple. Maybe there can be differentiation between cautious/skittish, aggressive defenders, and hunting monsters, as well as minion behavior depending on level of fanaticism or control.

I'll gather my ideas in my next post, but I wanted to hear if the community had any thoughts, or if there's already a supplement like this somewhere.

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The main things I consider when setting up an encounter include things like
  • How aggressive is the enemy? Are they just hungry and run away once there is significant danger or do they fight to the death?
  • What are the goals of the enemy?
    • Animals just want food, dragging off an unconscious PC to be eaten off screen works for them.
    • Animals can be desperate (or unintelligent) enough to keep attacking until dead.
    • Are they guards? Can they summon reinforcements? Are they just slowing down the PCs?
  • Are they trying to complete some activity?
    • Escape
      • Steal something not in possession of the PCs
      • Take something from the PCs
  • What are the enemy reactions going to be?
    • Can a fight be avoided, or do they attack on sight?
    • Are they defending or attacking
    • How likely are they to notice the PCs
    • If attacking, can they ambush
Along with a bunch of environmental factors that can impact the scenario. A black dragon in a swampy area that can immerse themselves completely to do hit-and-run attacks is going to be far more dangerous.

That's what I can think of off the top of my head anyway.

Why not simply call the shot of monster next move.
Depending on monster type you may inform different PCs Or ask for a check.

for a basic system I would use

establish Motivations for a Fight
  1. Food any kind.
  2. Specific food : blood, flesh, ….
  3. Gold
  4. Equipment
  5. guarding protecting
  6. Pleasure of destruction and killing
  7. establish domination
  8. slave hunt
  9. bounty hunt

Means to fulfill motivations

Looking for a TPK
Ransom, bully, negotiate
bravado, distract, lure
Take down one or two PCs And take them away

Morale, or how much monster will take risk
High but depend on a single leader monster.
Animal like


Ravenous Bugblatter Beast of Traal
I think this misses out on the strengths of having a human DM. How do you have them take advantage of various terrain and hazards? For all of the possible goals besides just "kill them all" that so many DMs boringly use? Then think of all the different charts you'd need for things of beastial intelligence, average intelligence, average intelligence and battle/tactical training, ones with superhuman intelligence. Those that will fight to the death vs. those that can break. Those that will pursue vs. those defending a lair. Following commands of leaders. Trained archers focusing fire vs. hungry ghouls going 1 on 1 and stopping to feast on the fallen.

I think you could put more effort into this then you will running combats for the rest of your life and find you still have an inferior result.


B/X Known World
A mix of old-school D&D for reaction rolls and morale checks with 4E's monster roles is almost* all you need. Reaction rolls to see what disposition the monsters have at the start of the encounter, morale checks to see how long the monsters are willing to fight (almost no one is willing to fight to the death), and knowing what role they take to decide on their tactics.

* The "almost" is covered by knowing what the monsters are doing at the scene and why they're there at that time. Generally speaking, unless the PCs' goals and the monsters goals are mutually exclusive they're not going to come into conflict...until the PCs mindlessly attack the monsters because they're monsters.

The mentioned The Monsters Know What They're Doing line of books is a great resource.


I like to have some idea ahead of time how things are going to react. If you don't have that, and need something to offload mental energy, use this:

  • If they are stupid (or you are going easy on the PCs), they attack whatever is closest, tie breaker being whatever is hurting them the most.
  • If they are smart, they gang up on the weakest/easiest to hit target they can get to.
  • If it's one monster, they flee when at half hit points and things are going badly.
  • If it's multiple monsters, they flee when half are dead and things are going badly.
  • If it's multiple monsters with a leader, the leader acts like one monster, the rest flee when the leader does.


Shouldn't each entery have a section on how they would typically act?
I think this is the right answer if you want to implement such a system. I get why people are arguing against it -- I would too -- but to take the thread at face value, i would say that you probably want a two dimensional resolution mechanic. One is based purely on the creature type. What goblins "want" in combat is different than what wraiths "want." At the very least you would need some broad categories, but in the end you would want individualized charts, I think. The second dimension is "scene motivation" -- that is, why is this fight happening? If you can create a matrix between those two things, you could have a pretty useful tool for helping the GM figure out what to do -- or for playing without a GM and making it feel spontaneous and consistent at the same time.

I don't think it is a terrible idea to explore. just know that it serves a different purpose that, say, the upthread mention "The Monsters Know What They Are Doing."

Good luck.


He / Him
I think this is an interesting idea! Even as a DM, rolling for enemy actions can create fun, unexpected results.

I could see something like creating different lists of 5 actions under the headings of different Descriptors, like Smart, Aggressive, Magical, Stealthy, etc. Then for easily-defeated enemies you choose two Descriptors (creating a list of 10 actions) and for more difficult enemies you choose four Descriptors (creating a list of 20 actions). The lists would probably have a lot of overlap.

It could look like this:

1. Attack the most dangerous looking opponent.
2. Attack the weakest looking opponent.
3. Make a powerful attack.
4. Gain advantage.
5. Display strength.

1. Attack from the shadows.
2. Attack with precision.
3. Find a good hiding place.
4. Gain advantage.
5. Confuse the opponent.

If you created enough of these you could just grab two or four for your enemies and roll on them for inspiration.

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