In early editions, there was a meta-game conceit that deeper levels of a dungeon held stronger monsters, and that players should gain a level of experience before delving deeper. Levels came from XP gained from defeating monsters, and players knew to seek out a few more low level encounters to gain treasure and experience before risking bigger challenges. Encounter challenge scaling hardly existed before 3rd edition. Modules would be designed for a range of three to five levels, and only achieved encounter balance by play-testing and the experience of the authors.
In wilderness adventures or adventures with a lot of player freedom of choice, you could engage in guerrilla war by attacking scouts and wandering monsters and guards at the entrance to every ruin and dungeon in the module until you were high enough level to start venturing deeper. Try it! Play the original Keep on the Borderlands module -- or the revised version for D&D Next, which harks back to those old days. There was value in grinding for XP, from a purely gamist perspective.
From a story perspective, not so much.
21st Century Editions
Starting with 3rd edition in 2000, the game's designers included level scaling and mechanics to scale the challenge of monsters upwards. These were separate (but connected) systems that had distinct (but related) effects.
The first effect was that every level, the GM had a system that, when it worked, made encounters consistently challenging. Gaining a level or ten didn't make the game easier -- but it made specific monsters easier. In 3rd edition, a single ogre is a nailbiter at level 1, a routine encounter at level 3, and too easy for the party at level 5. At level 5, two ogres was a routine encounter. At level 7, four was a routine encounter. At level 9, eight to ten ogres was a routine encounter.
The second effect was that the GM could scale a single ogre up in challenge level. An ogre was a nailbiter at level 1. An ogre (2nd level Barbarian) is a nailbiter at level 3. An ogre (4th level Barbarian) is a nailbiter at level 5. An ogre (6th level Barbarian) is a nailbiter at level 7.
Between these two effects, you could be fighting the same single ogre encounter every session from level 1 through 20.
4th edition dialed back on the ogres-with-levels but still provides versions of every monster at a range of levels covering at least half a tier (5 levels) or more. (Dragons, the game's titular monster, have remained a constant scaled challenge from level 1 to the highest levels in the game in every single edition. I remember making 36th level characters and trying to kill Tiamat in Original (BECMI) D&D.)
This means that in 3rd edition and later, there is no reason to grind for XP. The GM can just scale encounters on the fly to maintain their intended threat level by adding additional monsters or upgrading monsters to higher level versions. Most GMs will do this without thinking about it because the best GMs only stat out encounters one or two sessions ahead of time anyway.
So you may have heard of an ogre over the hill, avoided him for 2 levels, and finally came for him to find that the GM statted him as an Ogre (4th level Barbarian) last night because he was supposed to be a serious threat, and that's what it took to make him one.
There is No Advantage to Tracking XP for Levels
One presumed advantage of tracking XP for levels, for the GM, is to keep levels equally spread out -- one level every 13 encounters (3.0, 3.5, Pathfinder) or every 10 encounters (4th edition). But number of encounters is a very artificial measure of time! These encounters can come over 3 game sessions of 13; or 4 weeks or 9 months. So time consistency is a shaky reason at best. Why not plan to level every 6 months of real time? Or at the end of every adventure? Or every 10 game sessions? Plus, using XP for levels often results in gaining levels randomly in the middle of adventures, and then not at all at the end. It hardly feels like a reward if it comes at seemingly random times.
Another advantage of tracking XP for levels is to allow the players to "grind." Like in the old editions, they can pick off easy targets and fight wandering monsters until they feel like they're high enough level to tackle the challenge you, the GM, have placed before them. But doesn't grinding for levels just sound stupid in the context of modern day RPGs?
What is actually happening here is that your players are doing something they aren't interested in. All they want is the level. Giving them the level or scaling your challenges better is just as effective as running few sessions of make-work, and a lot faster. Frankly, with the CR system in 3.0/3.5 or the XP budget systems in Pathfinder and 4th Edition, you shouldn't have trouble scaling encounters to the PCs' level in the first place.
Plus, tracking XP is a pain. Recording the total every encounter, remembering to grant roleplaying awards, quest rewards, figuring out what rewards to grant for overcoming noncombat challenges, etc. What a hassle!
There is an Advantage to Levels
I wrote about what levels can do for your game in a previous post. Go read it! You can give up on levels (see E6, above) but you lose the neat things levels can do for a long term campaign, if used well.
The Conclusion: Don't Track XP, but Grant Levels
Here are some ways to grant levels without tracking XP. These are suggestions that came out from the various players and GMs who responded to my questions on twitter and facebook.
- Level Democratically: At any time a player (or the GM) may move that that party should gain a level. The players (and GM) vote yea or nay. Simple majority rules. If the majority votes to level, the party gains a level. You'll find your players will be very reasonable about this.
- Level on Schedule: Every 10 sessions, every 6 months, or at the end of every quest, the party gains a level. Tailor your schedule to your group's logistics. Do you play 12-hour sessions every other month? Then level at the end of every session. Do you play 3-hour sessions every week? Then level every 3 months.
- Level after X Achievements: A lot of bloggers have talked about using achievements in D&D. A DM I'm playing with is starting to use them. These run the gamut from system achievements (Shot in the Dark: Score a critical hit against an enemy with total concealment against you) to flavor achievements (Beastmaster: Rescue an abused animal or monster and make it your companion) to story achievements (Stacking the Deck: Discover the secret collector and take their cards so they cannot assemble the Deck of Many Things). Use these for levels instead of XP. Each achievement adds to the party total. If I used this, I would prefer a mix of flavor and story achievements. The flavor achievements may be scored once per player character, and the story achievements are unique. Flavor achievements encourage the players to take actions that reflect common tropes in the genre you're trying to promote. Want horror? Use horror achievements: "I'll Be Right Back: Go investigate a disturbing sound all on your own." Want epic fantasy? Use epic fantasy achievements: "Tolkein Bluster: Recite the history and destiny of your legendary magic weapon when intimidating foes or exerting authority. Counts double if gets so purple and melodramatic that it earns a slow clap from the table."
- Level at Milestones: Whenever the party makes a major achievement in the game, give them a level. This includes completing adventures as well as completing major goals within longer adventures. If you're running Madness at Gardmore Abbey, give them a level for completing Sir Oakley's quest chain, Lord Paedrig's quest chain (which includes Berrain Velfarren's quest chain), and when they finally assemble the Deck of Many Things. That's 2 levels during the adventure and one at the end. This technique lets you run modules without having to adjust encounters. A common problem with modules is that by inserting player plots, or running stuff off the rails when the players go wandering off, you often wind up with too much XP, and PCs of too high level for the module's end. Unless the players abandon the module entirely and come up with a goal that means more to them than the module's quest, don't give them a level until they achieve the module's milestones. (If they do hare off and choose a new quest, ignoring the module... well, you've got to abandon the module anyway.)