I'm a campaign designer and DM with 20+ years of AD&D 1st edition experience. I've been "retired" from the game for over a decade, assume I don't know anything about 2nd, 3rd, or 3.5.

Now I'm co-authoring a campaign with my professional illustrator/daughter.

What are the most important differences that I should watch out for when DMing 4th edition? Where are my assumptions about gamemastering likely to be wrong. I don't mean simple mechanics stuff, like tables and AC have changed - I mean potentially problematic changes in the very gestalt of the game...

I've now played an Encounters session and have an example: The rhythm of combat seems different, with maintaining status effects (and saving throws) being more important. It feels more like a video game (World of Warcraft) with less options but more powerful ones.

What else?

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    \$\begingroup\$ The options are more diverse than 1e had in a slightly confusing way. To give the players the ability to affect the plot you need to go outside the rules and make it up just like you did in 1e, but 4e fills in more of the combat playspace and so it's less obvious that you should just go outside the rules in the book, and 4e players don't generally expect that it will happen as much. \$\endgroup\$ – Lokathor Oct 23 '10 at 2:19
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    \$\begingroup\$ I suggest you join the growing Old School movement, and not chase the fleeting 'current standard' (which will change as 5e, 6e, and more appear in the future). \$\endgroup\$ – ExTSR May 25 '11 at 17:20
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    \$\begingroup\$ When you say "co-authoring" do you mean writing a campaign setting book for publication or running a campaign along with your daughter? \$\endgroup\$ – cr0m May 25 '11 at 21:51
  • \$\begingroup\$ We are actually working on a campaign wiki with hopes of [self?] publishing it some day. We're also likely to co-gm the game as it is pretty NPC-story heavy... \$\endgroup\$ – F. Randall Farmer May 25 '11 at 23:15
  • \$\begingroup\$ Hey @ExTSR, I resemble that remark! I grabbed oldschooldm.com to hold forth a few thoughts as we get closer to publishing our campaign log. \$\endgroup\$ – F. Randall Farmer May 25 '11 at 23:16

Points of Light

The 4E Dungeon Master's Guide defines the parameters of a typical D&D campaign in the setting section. The default setting is called Points of Light, which describes how the world is mostly wilderness, full of monsters and ancient ruins, and peppered with occasional safe havens (typically villages and small cities).

Exception Based

The 4E game is exception based. Where AD&D defines rules for this and rules for that and a different class might have its own system (e.g., thieves), the core 4E rules are very simple. On top of that very simple core, add exception after exception. If you've played Magic: The Gathering, you've seen this principle in action.

To great effect, 4E defines classes primarily with powers. Every class works pretty similarly in this regard. The difference is in the list of combat powers that defines each class. Each power provides an exception to one or more rules, to be used in specific combat situations.


Most versions of D&D have some idea of non-combat skills that any character can learn. In AD&D 1st Edition, it's the "secondary skills" table in the DMG. In 2nd Edition, it's non-weapon proficiencies. 3E and 4E add a true skill system. The game calls for you to roll these skills all the time. 4E adds a skill challenge system for handling non-combat obstacles that require effort over an extended duration.

I and many other people love the idea of skill challenges but hate the 4E implementation. Find Stalker0's Obsidian Skill Challenge system and use it instead. It's fantastic and solves all my problems with the built-in system.

To Level 30, Tiers

AD&D didn't have level limits, but it got pretty unwieldy after a certain point (some say 6th level). By unwieldy, I mean that the DM's effort to create encounters just gets harder and harder as the characters level up. 4E makes encounter building a lot easier.

4E also takes the characters to level 30 with clear sets of powers for each level. It does this in three, 10-level tiers: heroic (1-10), paragon (11-20), and epic (21-30). Play changes a bit at each tier, and the kinds of encounters PCs face (and where they adventure) changes considerably.

Dynamic Combat

AD&D combats mostly turn into characters in fixed positions trading blows with monsters until one side loses. There's not a lot else going on. In 4E, the standard/move/minor action system gives players a lot of options every turn. A typical round for a rogue includes moving around (avoiding opportunity attacks by shifting), attacking, and maybe some kind of minor action to boot. A lot happens in six seconds! (Oh yeah, combat rounds are six seconds, not a minute.)


4E is way more gonzo. Or laser-sharked. Whatever term you use to describe it, 4E has lots of weird races and classes as PC options. Play a goliath ardent, a dragonborn sorcerer, a tiefling warden, etc. The old races and classes are still there; don't worry. Just expect spikes and horns on everything (not really, but it sure feels that way).

Power Sources

4E introduced the idea of distinct power sources to the game. AD&D differentiated between types of magic, and dumped illusionist magic in with magic-user magic but separated them from clerical divine magic. 4E gets explicit about where a character's power comes from, even if he's a fighter. You have the martial power source for fighters and rogues, the arcane power source for the magic-user types, divine magic for the clerics and other religious types, primal power for druids and the like, and the psionic power source for a host of mentally-driven characters.

Defenses, Saves, Death

All different! Be careful here.

You have four defenses: Armor Class, Reflex, Fortitude, and Will. Basically they took effects that used to require a saving throw to avoid and turned it around. Now you have a defense against those things. The fireball attacks your Reflex. The illusion attacks your Will. You don't have to roll anything to avoid it. They either hit or not.

And while we're talking about AC, gone are AC to-hit charts and THAC0. You roll d20 + bonuses and try to meet or exceed the defense (AC or otherwise) to hit. Simple enough.

Saves still exist, but they're for shaking off lasting effects. Say you're taking ongoing damage from being on fire. At the end of your turn, you get to try to save against the effect. All saves are the same: roll d20 and get a 10 or higher. Simple as pie. Mmmm, pie.

If you fall under 0 hit points, you're unconscious and dying. Every turn in combat, make a saving throw. 10+ and you don't get worse; 1-9, and you get one strike. Three strikes, and you're dead. Roll a 20, and you get to use a healing surge! Oh, the negative-10-and-you're-dead thing changed. Now you get to go negative equal to your "bloodied" value, which is half your maximum hit point total. Pretty sweet.


In general, 1st level characters are pretty damned tough. However, the monsters they face are pretty tough, too. Your 1st level rogue might have 23 hit points, but the kobolds have 27. (Just making up numbers, but you get the idea.)

Encounter Scale

Encounters in AD&D (and really every version before 4E) were pretty much focused on one small area, typically a single room. You go into the 10x20 room and fight monsters. 4E encounters sprawl over multiple rooms because of all the extra movement. It really feels like a big fight, dragging in monsters who overhear the noise. Or you might loop around the back way to flank the boss.

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    \$\begingroup\$ Expect there to be a lot more combat. Some of the things you used to do in 1e are kinda impossible in the more-constrained rules set, but characters will have more combat superpowers. \$\endgroup\$ – mxyzplk Oct 23 '10 at 1:01
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    \$\begingroup\$ Bah, nothing is impossible. 4E just doesn't have rules for some of that stuff. In fact, AD&D didn't have rules for a lot of that stuff, either! ;) \$\endgroup\$ – Adam Dray Oct 23 '10 at 1:04
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    \$\begingroup\$ At the same time, remember the improvisational nature of AD&D. 4e draws on the same heritage and explicitly promotes "winging it" with some guidelines found on page 42. \$\endgroup\$ – Brian Ballsun-Stanton Oct 23 '10 at 3:06
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    \$\begingroup\$ Great answer. I would add Keywords. The first edition did not rely on keywords at all. When moving to 4e pay attention to keywords, they convey a lot more information than just reading would intuitively provide--they use it to pack a lot of information into a small space. \$\endgroup\$ – Bill K Oct 26 '10 at 17:32
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    \$\begingroup\$ It's been awhile since I asked this - let me reinforce the "encounters scale" section. Monster defenses are not based on the type of physical defense they have (chitin, or soft flesh) but on the power of the PCs likely to attack it (based on monster level). That was a big surprise at first. \$\endgroup\$ – F. Randall Farmer Sep 12 '11 at 23:12

Rules over color - Lots of mechanics, especially characters powers, should be interpreted as rules first, color second. If you have a power called "foot sweep" that creates the status "prone," that's what it does. It doesn't matter if the target is a gelatinous cube, it still works. If you start ruling that things don't work because it doesn't make sense, you're weakening powers that the players were looking forward to using. But, this is actually okay, read on...

Combat is abstract - It looks like a simulation focused game with the miniatures and squares, but it's more abstract than it looks. It focuses on the general ebb-and-flow, as well limiting things to keep flow exciting, even at the expense of "realism." This is why areas of effect are square, not round(ish). This is why the height rules are very simplistic. This is why the rogue can only throw a flurry of daggers once per day, and why he only needs one dagger to do it.

Given those assumptions, how do you play? This is just one option, but it Works For Me:

Describe to justify the rules - The above doesn't mean the game has to degenerate into a tactical wargame! 4e can very easily turn into a wargame where people just read off power names and announce numbers. The key is to craft narrative to explain what is happening, don't just let the mechanics work. Don't get too attached to the color text associated with each power; they range from the uselessly abstract to the inappropriately specific. Instead think about what the rules say happened, then figure out what it might mean. You "mark" the guard? What does that mean? It might mean that you shout a stream of insults at him. It might mean you constantly feint toward him. It might mean you're circling around him (remember, combat is abstract!). How do you trip a gelatinous cube? Well, you probably don't. But the "prone" rules suggest a brief period of immobility and exposure. Maybe you grab a broken door or table from the floor and shove it in, slowing the cube down. (Where did the table/door come from? Combat is still abstract, it must have been there all along.) Maybe you smash into the cube briefly (with weapon or a shield or the aforementioned table/door to protect yourself) causing the cube loose cohension, forcing it to take a moment to reform. If you wed yourself to the name of the power and the color text, you'll frequently have no idea what happened in the game's fiction. But if you're willing to improvise, it's very rare that you can't give some sort of heroic explanation.

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    \$\begingroup\$ +1 Rules over colour. This, a hundred times this. If this had been explained up-front instead of left to be "obvious" or "discoverable", how different the discourse on editions would be… \$\endgroup\$ – SevenSidedDie Nov 1 '10 at 21:05

Quite simply put: treat it as a wholly new game.

It shares the same base range of stats. It shares the use of 1d20 to hit. Otherwise, it's almost entirely different mechanically.

That leads to a wholly different gestalt in play.

The game has strong niche protections, stronger than 1E, and in different niches from 1E (tho there is overlap).

The biggest trip up will be the reward cycles.

In older editions, the only explicit reward cycles are XP, and long term rest (which grants healing); treasure has guidelines provided linked to the monsters, but those guidelines are explicitly not hard rules.

In 4E, there are more explicit reward cycles. The XP cycle is much the same approach, tho much more regulated. The healing surges and various length rests are a form of reward cycle. The awarding of treasures in 4E is VERY different, in that it's both much more essential in the designer's mind, and also thus more regulated in rules. Treasure awards are scaled to the characters, not just the threats, so the need for balanced encounters is actually stronger.

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    \$\begingroup\$ Every game has a reward cycle. D&D 4E's reward cycle is 1) build a cleverly-built character, 2) test that character in the fires of adventure and combat, 3) earn XP to level up, 4) repeat. I don't know what @aramis is getting at in particular. 4E has basically the same reward cycle as AD&D 1E, but it's definitely tighter and more clearly focused. \$\endgroup\$ – Adam Dray Oct 23 '10 at 16:15
  • \$\begingroup\$ @Adam: you misunderstand the term. it refers, in this case, to more than just XP, but in treasure, magic items, and expected reward, as well as needed reward. 4E has explicit reward cycles in terms of treasure based upon the characters, whilst pre-3 D&D leaves treasure generally to the GM's whim, with guidelines by monster type. \$\endgroup\$ – aramis Oct 23 '10 at 20:41
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    \$\begingroup\$ A "reward cycle" is not a rule; it's a gaming psychology concept. DMs encourage players by giving them "rewards" when they do well. A reward can be anything from treasure for an encounter to XP for writing a neat backstory. The reward cycle in a game describes a regular pattern where the player can get new rewards each time they do X... go up a level for every so many monsters they beat, for example. \$\endgroup\$ – RMorrisey Oct 23 '10 at 21:54
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    \$\begingroup\$ I was just trying to explain that you can't look up "reward cycle" in the rulebook, because it isn't there. \$\endgroup\$ – RMorrisey Oct 24 '10 at 17:29
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    \$\begingroup\$ @RM: you prompted me to be more explicit in what they were... @FRF: RM is right, the term isn't used in most games rulebooks. It is, however, a process encoded strongly into most rulesets, and different reward cycles tend strongly to result in very different play experiences. A game which rewards killing equally with driving off tends to be played differently than one where driving off is worth half as much or twice as much. Players who realize a given behavior costs them various rewards usually avoid those behaviors, or perseverate and then grouse about broken rules... \$\endgroup\$ – aramis Oct 25 '10 at 6:06

Combat takes longer. I can't stress this enough. Once you initiate combat you are committed for the next 1/2 hour or hour resolving it if fought to the finish. In a four hour session the most I seen somebody do was resolve three combat encounter between the same number of roleplaying encounters. This can be a big shock for somebody used to 1st edition AD&D or OD&D. I was used to it because of GURPS so it wasn't a big deal for me.

Wizards had opted for a specific style of presentation for 4e adventures. One that most of the 4e community has come to expect. If you use pre-made adventures they will seem constrained and linear compared other RPGs. The good news is that the individual encounters are often well written, challenging and fun. Another benefit of 4e is that it lays out the math for you. So you can vary quickly come up with encounters of whatever power levels.

Remember you don't have to run 4e the way the Wizards presents it. If you have any experience with other RPGs with tactically detailed combat system whatever technique you had developed will work well with D&D 4e. I found how I managed GURPS worked fine with D&D 4e.

I typically run a sandbox campaign. And whether it is GURPS, Fantasy Hero, Swords & Wizardry or my original AD&D 1st the setting is what it is and players encounter whatever I decided was in the locale. What this means in practice is that around 5th to 6th level (or double GURPS starting points) most of the encounters are underscaled. Only when they go to truly dangerous areas or encounter experienced enemies will they find anything comparable to their current skill level. The effect on my GURPS game and the few D&D 4e game I ran is that most combat encounter are quickly resolved.

Hopefully this illustrate that there is more than one way of running 4e than what is typically talked about. The only part of D&D 4e that is hard to work around is the how the power system makes everything seem like heroic high fantasy. But that is a minor issue. Again pretty any type of style or plot that you ran in AD&D 1st you should be able to do in D&D 4e. Adam's post is a good rundown of the technical aspects of 4e.


A rules set cannot cover every possible action that can be imagined by the minds of the participants.

To be overly simplistic:

Old School refrains from curtailing options and requires the GM to create and apply methods of resolution. New School attempts to codify almost all actions while encouraging the participants to think within (and self-restrict themselves to) the given limits.

In "old school", anything not expressly forbidden is permitted.

  • The unlimited nature of play means that the GM must quickly assign (or negotiate) a mechanic to resolve an unexpected situation, apply it, assess the results (in terms of Fun, Coolness, Plot, et al.) and then alter or tailor the results to fit. Old School 'rules' (guidelines) are incomplete, forcing a lot of extra work on the GM, who may not be up to the task.

In "new school", anything not expressly permitted is forbidden.

  • The restricted nature of play means that both the GM and the players must think and plan within those strictures, attempting only those actions, and must rationalize incongruities (see @AlanDeSmet above). New School rules often attempt to be complete to minimize bad discretionary calls by the GM, but thus create their own problems in this regard.
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    \$\begingroup\$ there's no doubt that having a lot of specific things a player CAN do in 4e leads to this over-generalization. This misunderstanding was causing me a lot of grief during the first few sessions. Might I suggest you formulate this answer as it's own question? I'd love to hear what other 4e DMs have to say and what citations they give to support their response. \$\endgroup\$ – F. Randall Farmer May 25 '11 at 23:34
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    \$\begingroup\$ I don't think this is true at all. I think you have to start with a pretty hefty set of preconceptions to assume that the rules in 4E give way to this. What the full set of 4E rules means is that, if your players or the DM want to improvise, the DM has to outrule powers by Rule Of Cool sometimes. \$\endgroup\$ – Adriano Varoli Piazza May 26 '11 at 20:41
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    \$\begingroup\$ It is perhaps more fair to say that -- disregarding trivial milieu-based limits (e.g. you can't use a pistol 'cause they haven't been invented here) -- in much of NewSchool players & DMs are trained to think within the rules matrix and to not imagine more broadly, while Old School is the reverse. Both extremes have their plusses and minuses. \$\endgroup\$ – ExTSR May 27 '11 at 14:33
  • \$\begingroup\$ I'm not sure this answers the question... Could you possibly expand on the difference you have observed and explain what practical advice based on this difference would be useful to an AD&D DM adapting to fourth edition? \$\endgroup\$ – GMJoe Oct 24 '13 at 5:07

Lots of good answers—may I just add some things I ran into when I was learning that might help you learn? Not so much differences, but things to pay attention to.

Keywords. 4e is keyword crazy and they all mean something Very Specific. Get used to identifying when a keyword is being used and take care in reading the definitions—don't just skim.

What you can and can't do is outlined much more clearly in 4e—it can almost become a game of DM vs. players where a DM can put his all into the strategy of a battle and still not win. Of course, a DM can re-write any rule he wants, but a DM who tries to follow the rules will find himself with much less freedom than in 1e—however this makes DMing simpler because there are fewer judgement calls. When someone is hiding behind a pillar there is a stack of very specific rules that tell if he gets cover, superior cover or neither, weather he can occupy the space or cut across it when moving, etc.

4e really isn't 1e. I like it but it's more like 60% tactical table-top game and 40% RPG.

If you want some exposure, hit a local game store on Wednesday nights and look for a D&D Encounters group. Watch or join. It's a good quick intro to the rules with no commitment.

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    \$\begingroup\$ @Adraino What I mean is that the rules are so well specified that the DM CAN BE as restrained as the players and that makes it easier for the DM. It doesn't mean you have to or should play like that, it just means that the rules specify much more detail than in other RPGs I've played, to the point where if the DM wants to constrain himself to the rules as written, he can go all out with a monster and still not kill the characters. In other editions there is always a lot of "Well, it looks to me like you have cover" and "I don't think ou can hit him because of the angle"--none of that in 4th. \$\endgroup\$ – Bill K May 31 '11 at 1:49
  • \$\begingroup\$ @Adraino Perhaps ExTSR's explanation of this is better--simply that it's gone from "Anything not forbidden is permitted" to "Anything not permitted is forbidden" making much less choice for the DM. I wasn't saying it was bad or good or that the DM shouldn't override rules, I was just saying it was a different approach. \$\endgroup\$ – Bill K May 31 '11 at 1:53

I think you have a lot of good answers about the rules. My favorite recommendation here is: "treat as if it were a whole new game". In that sense, there is also a lot of flavor changes:

  1. You may play Tolkien fantasy, but it was designed for a WoW fantasy style.

  2. Old school adventures featuring a dozen of deadly traps and sequential combat aren't recommended. (The rules make it harder and the players' frustration level rises very quickly).

  3. You may limit the players' choice of races to a "classic" subset, but there's a lot of fluff to explore with new races and the "Mos Eisley Cantina" effect.

  4. Every power has a fluff and they are quite elaborated. Magic is more common. Strange races and languages are quite normal. Sometimes it may take a little more imagination to get the "Owww effect" when describing something.

  5. The game was thought to be played with props, miniatures, maps, etc. Take a look at the Sly Flourish website for good examples: http://slyflourish.com/.


The most important thing in my view, is if you're not running organised play, don't actually change much. The biggest complaints I have with D&D4e and I've heard from others would be fixed by a DM who's running the game in a flexible AD&D style, and I've had excellent experiences with games run that way. The rules are good, the restrictions are unnecessarily restrictive though, so letting players do stuff not explicitly allowed in the rules really contributes to a lot of fun. It's not something that a 3.x DM would likely pull off as well, but as an AD&D DM you have a unique opportunity to interpret the rules differently and give a better experience for everyone at the table. Don't look up rules in details, or sweat over definitions, analyse proposed actions within the framework provided by the rules with common sense instead.

It's kind of opposite of what most people would suggest given the changes brought about in 4e, but in home play it really doesn't have to be played the same as an LFR game.


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