DM’s Guide to Converting 3E Adventures to 4E

Lately I’ve had a dilemma: my D&D group wants me to run D&D fourth edition, but I’ve got three years of Dungeon magazine back issues full of unused adventures for D&D third edition. There’s a lot of excellent adventure material in there (around a hundred adventure modules in all), enough to run a level 1-20 campaign several times over. My solution has been to try and convert some of these third edition modules to D&D 4E.

It’s not an exact process, and I’ve only converted a few modules so far, but here’s what I’ve learned about converting 3E adventures to 4E.

Monsters

The most significant change I’ve noticed is in monsters and monster encounters. In addition to a radically different monster stat block format, 4E introduces a shift from one or two monsters in an average encounter, to perhaps four, five or more. There’s greater attention paid to how different monsters work together, such as combining two ranged attackers (like wizards) with tough melee attackers (like fighters, hobgoblins or ogres). Several monsters either don’t exist in the 4E Monster Manual, or have radically changed in level from their third edition versions.

You’ll need to change most monster encounters, usually adding more monsters or using different creatures altogether. The goal is to keep the general feel and purpose of the encounter, even if you completely change the number, level or type of monsters encountered.

  • Single monsters (boss fights): Single “final battle” monsters should become a Solo of the appropriate level. You can add a few minions to round out the XP total.
  • Single monsters (non-boss fights): Don’t use Solo monsters for this - they’re for time-consuming, resource-exhausting final battles. How you apply this monster depends on the type the creature’s “role” in 4th edition (see DMG p.54):
    • Artillery/Controller: Use two of the creature, or apply a template to bring it up to Elite. Additionally, give them some bodyguards, such as soldiers, skirmishers or brutes - even a powerful mage on his own is quickly defeated.
    • Brute/Soldier: Either upgrade the creature to an Elite and give him non-elite underlings of the same type, or use a group of several.
    • Lurker: Like artillery, lurkers are easily defeated in a straight fight. Have them hide and attack from the rear when the players enter a real combat.
    • Skirmisher: Use a group of several of the creature. Instead of one displacer beast, use a pack of five or seven. If the creature is too powerful, lower it by a few levels using the guidelines on DMG p.174.
  • Paired monsters: You can keep the pair by using two Elite monsters of the appropriate level. Add a template to existing monsters to make them elite. You can give the monsters minions to found out the encounter, if it fits.
  • Pack of monsters: A group of similar monsters (wolves, kobolds, etc) can usually be played as presented.

Use the Encounter Level in the original adventure as your guide. An EL6 encounter (say, two CR4 creatures) becomes a Level 6 encounter (1,250XP for five PCs). Remember that while third edition challenge ratings refer to one monster, fourth edition level assumes a monster group of around one per party member. In some cases this converts exactly - for example, five CR1 ghouls is EL5, ghouls in 4E are Level 5 so five is an average Level 5 encounter. In other cases you can simply add more monsters (if the 4E equivalent is weaker), demote them to a pack of minions, or change the creature’s level up or down by as many as five levels using the guidelines on DMG p.174.

If the monster is too different, or doesn’t exist in 4E, you have three choices. The first is to use the stats for a similar monster, but keep the current monster’s appearance - for example, create an Iron Golem by taking the stats for a Stone Golem, perhaps adding a few extra levels, or a template, or changing a power or two. The second is simply to use a different monster entirely, preferably one that keeps the same feel and purpose as the original. The third is to create a new monster from scratch, using the guidelines in the DMG p.184-185.

NPCs

NPCs only need game statistics if they’re going to engage in combat. When they do, creating an NPC statblock from scratch is straightforward. Use the guidelines in DMG p.186-188. Most core 3E races already have a fourth edition equivalent, even monster NPCs (DMG p.192-183, or MM p.276-277).

There is an issue with NPCs who require specific abilities, such as illusion or divination spells which don’t exist in fourth edition (yet, anyway). In that case you can adapt the character by giving those abilities as powers, rituals, magic items or other abilities. Not every character in D&D has the same abilities and limitations that player characters do; perhaps their ability is a rare inborn talent, or learned after decades of painstaking study, or too costly in feat or power slots for player characters to choose it.

Remember not to give a character too many powers, even if the rules permit it. An NPC might have as many as nine or ten powers, but they’re unlikely to survive long enough in a battle to use them all. Four powers is a good number.

Terrain

Although third edition certainly had terrain, fourth edition gives it more attention. If your dungeons have features like furniture, water, steep slopes, submerged areas, lava flows, rocky ground, hanging chandeliers, wall tapestries, chambers full of improvised weapons or anything else, consider what effect those might have in battle. If many rooms have no special features, consider adding some. Perhaps the dungeon denizens have set up a few fortifications since they moved in.

Make sure your dungeons aren’t too cramped. A choke point in a narrow corridor makes for an interesting challenge now and again, but cramped battles stop player characters from using many of their movement-based abilities.

Traps

I have to admit that I haven’t done much trap conversion. An approach which seems to work is to convert the trap directly. Treat a CR2 trap as a Level 2 monster, and simply keep the attack and damage the same. Convert saves to attack rolls: a fireball trap dealing 8d6 damage (Reflex half DC14) becomes +4 vs Reflex, 8d6 fire damage, dealing 4d6 on a miss. This method seems to work, but may require more refinement.

Magic Items and Treasure

Magic items and gold are now handed out in different proportion. Generally speaking, you’ll want to scrap all the existing treasure and replace with fourth edition style treasure parcels, arranged as closely as desired to the original treasure. Important treasures should be slotted into the existing system; for example, if a level 5 magic item is in one of your treasure parcels, you can use that for the villain’s weapon.

Certain items have changed dramatically in power or no longer exist in fourth edition. Wands, scrolls and potions of most spells are gone. Where items no longer fit, replace them with more appropriate items. If an item is vitally important to the quest but is too powerful for the player characters’ current level, replace it with a cursed version of that item which functions normally but has a drawback that discourages regular use.


Comments (3)

Aaron (June 3rd, 2009)

That’s awesome! My first adventure I ever played in 4e (and technically my first real RPG experience) was a very poorly converted Pathfinder module (Hollow’s Last Hope, I think), so it’s good to see that someone has some guidelines for it. Plus, I was just about to look at converting another 3.5e adventure.

Thanks! Your website always has some awesome stuff!

Aaron
allgeektout.com

Chris Cumming (June 3rd, 2009)

Great article. I’ve done some conversions of 3e modules as well, so far Tales of Zobeck and Dungeonaday.com. I’ve come across a couple of additonal points. One is increasing the size of the squares from 5ft to 10ft and grouping several rooms together into one 4e encounter to make combat flow easier. And the other is to look for ways to convert sections of the adventure to skill challenges such as the investigation or interrogation portions of the adventure or some of the interesting encounters.

Thanks,
Chris
1001bobs.weegamers.com

mike (June 5th, 2009)

It’s interesting converting campaigns to 4E. I’m running my group through a converted version of Dungeon’s “Shackled City” adventure path, and the biggest change I’ve noticed is that rooms need to be 50% or 100% bigger than their 3.5 counterparts.

Also, you run into a lot of things that you have to just hand-wave to make sense. For instance, a major plot point in the campaign is the recovery of some wands of control water. However, there is no such spell in 4E (and thus, no such wand).

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