Most RPGs have an element of combat within them and as the GM; you are in charge of planning the strategy of the enemies. The combat portion of an RPG really seems to be the point where the Players versus the GM mentality originate since the enemies are attacking the players with the intent to get rid of them. With this in mind, a GM needs to be mindful that the combat situations set in front of them are not too simple that combat is a bore, while also making sure that the situation is not unwinnable (unless there's a purpose to that – but that will be addressed later).
As a GM, where do you start when planning combat situations or encounters? Depending on the RPG you are playing, there may be tools out there to help plan out challenging encounters. Since I know Dungeons and Dragons best, I know there are a few different tools to help plan out encounters for 3.5e, 4e, and 5e (D&D Next). Each edition handles calculating difficulty of enemies a little different, so what may work in one edition may not always work for another. Regardless though, each encounter should have some element of planning behind it.
Personally, I am not a GM that has encounters happen without a purpose. If a party is encountering something, it is generally because there is some element of story behind it. While there could be encounters stemming from anything, I tend to stray away from the world versus the player aspect where anyone or anything could become hostile at any moment. This does not mean it is wrong to run your campaign that way. Many GMs that I know use random encounters as a way to encourage the players to keep moving or as a consequence for an action. For example, if a party member wants to go hunt for food, they may stumble across rival hunters that were hunting the same quarry, or possibly, they may try to take down something stronger than they are and combat may ensue.
Random encounters are a bit more difficult to plan since they do tend to be a bit more spur of the moment, but outside of that, most encounters can and should be planned out. Bill Cavalier (@dungeonbastard on Twitter) tweeted a list of things that you should have when you plan an encounter: purpose, quick impressions, discoverable details, main obstacle, complications, outcomes, and connections. Each of these should have some consideration to it and sometimes one facet will have more details than there was on a previous encounter. Just as an example, I will fill out a quick prep sheet for an encounter so you can get an idea of how to plan an encounter using Bill Cavalier’s method.
Here is the situational scenario: The party is searching for a shipment of coal that was taken by a band of goblins. They know that the coal was in a handcart and they followed the ashen footprints and they can currently hear goblins talking/whimpering ahead just outside of the tree line.
·
Purpose
Purpose
o Assuming the group approaches the goblins, they will prepare to attack since they believe that the party is going to try to steal their coal. (Note: There is a chance that the party may want to talk their way through this. In that case the goblins want treasures and unwillingness will just make them angry and wanting to attack more).
· Quick Impressions
o The Goblins are mostly busy loading coal into an airship that seems to billowing thick black smoke. There are 12 goblins, four are carrying bows (watching the tree lines), six are carrying shovels (treat as clubs), and two are in armor and seem to have some sort of weapon on their persons (they are standing on the airship directing the goblins with shovels).
· Discoverable Details
o There seems to be three carts of coal, all with the same company name on it “Sootworks”.
o One of the 2 goblins on the ship has a book chained to his belt and he seems to be reading over it as the goblins load the coal (Book of maps/legers)
· Main Obstacle
o The party must get the coal before it is loaded onto the airship or before it flies away.
· Complications
o Once spotted by the archers, they will be fired upon and the effort to load coal will continue faster unless goblins are killed.
o The airship has two loaded harpoons on it that can be used to fire at the party if it lifts off before they stop the m.
· Outcomes
o If successful:
§ They can discover that the book has a number of sales to them from “Sootworks” the group that sent the party over to investigate the stolen coal – Book from one of the Goblins on the airship.
§ They can deliver the coal back
§ Loot: 60GP, two shortswords, four poorly crafted bows.
o If airship flies off:
§ They only have the information that there are three “Sootworks” carts left without any coal.
§ Depending on how quickly they flew off they may have left some coal behind.
· Connections
o Sootworks is the company issuing the mission. Why would they be working with Goblins to sell coal and what would make the Goblins steal coal (if they even stole it at all?)
· You know why this encounter should take place (Purpose).
· You know what things to mention about the situation before the encounter starts (Quick Impressions).
· You know what details can be discovered by spot, listen, perception, etc. checks or from later checks when looting (assuming they are successful) (Discoverable Details).
· You know the objective of the fight (Main Obstacle)
· You know what will make the party’s objective difficult (Complications)
· You know what the success and failure criteria are and the results of each (Outcomes)
· You know how this encounter connects to the rest of the story. (Connections)