Adapting older modules for 5e

Adapting older modules for 5e

Adapting older modules for 5e is a challenging but fun task. You may want to share your experiences of older modules with new players, but doing this is hard.

Adapting older modules for 5e is hard. You will have to learn how to convert hp, abilities, saves, original concepts, and more.

I have adapted a few older modules for 5e and am currently adapting the old module ‘Expedition to the barrier peaks.’ I have done this a few times and most 5e modules that try to re-create old modules miss the mark. They make the monsters easier and just take away from the core of what made those adventures memorable. You will learn how to not do that today.

The soul of older modules

The re-imagining of AD&D’s Tomb of Horrors for 5e was done poorly. The Tomb of Annihilation is nothing like what was intended. You can argue that this is a good thing, but the whole point of the Tomb of Horrors was to make players think or die. Yes, it was at a different culture and time, do players want the older module experiences or an easier/newer one?

This is a question you need to know the answer for adapting modules for 5e. If you have a group who wants to really play Ravenloft or Tomb of Horrors the later editions do it poorly. Players will not get the real experience if they play with later editions.

That is why you might want to re-create older editions modules by only adjusting stats. But there is a problem.

The older modules were made for a different time, and have a foreign system. This system is not compatible with 5e for most things!

Saves are done completely different with a 90% spot, 1/6 spot, or save/die mechanic!

Things were a lot harder because the system was not as refined, or had skill checks. They did the best with what they had, and this is where you need to make a decision.

How faithful do you want to be?

Why an older module?

When adapting older modules for 5e you have to ask why? Why go through all this trouble? What was it that made you want to share this older module with everyone?

Was it the terror that you felt? The need to think and be strategic or die? Maybe the sheer ridiculousness of what you had to face made you want to share this with everyone. Even if it was just the loot, you need to figure out why you are doing this.

Once you find your answer, you know what cannot be compromised. If you are looking for an authentic experience of how difficult the older modules used to be, keep the instant kill traps.

If you, on the other hand, want to share what monsters and ideas were in the module, you can take out the instant kill traps.

This is what you need to decide on!

I will help you learn how to adjust hp, convert saves, and everything else but you need to know why you are adapting older modules for 5e. Once you know the reason you can make a faithful adaptation. If you do not know why then you will make something like the Tomb of Annihilation.

Now that the most important thing is out of the way, let’s get into how to adjust some concepts.


When adapting older modules to 5e you might have noticed something right away. The hit points on monsters. They are generally very low and don’t always do a lot of damage. HD or hit dice are the closest thing you had to CR (challenge rating) back then.

HD for a creature is generally 1d8 per HD.

This is actually what it says in the old Monster Manual.

Now while HD was the closest thing to CR, it is not comparable difficulty wise. A CR 2 mimic had 7-10 HD while a CR7 mind flayer had 8HD. There is no magic ratio to go by, so I highly suggest to go by milestone leveling. If you want to use exp then it is up to you to figure things out.

In the earlier editions, magic and abilities were given out as extra exp to compensate for the much simpler CR system that we have now. That is why it is best to just adjust the HP to whatever the creature is in the standard monster manual. If you are going to adjust exp though, always consider extra/magical abilities as a huge boost in CR while HD isn’t that big of a factor.

This doesn’t always work. There are some monsters that were not converted. For these monsters, I suggest increasing their health by 10, 20, or more until it ‘feels’ right. I know this isn’t an exact science, but if you are converting modules hopefully you are experienced now and can realize when something is or isn’t right.

You won’t always get this right. That is why I suggest giving a new monster less hp than suggested just in case. You can always adjust it in the fight if you feel it needs it.

But what about abilities?

Strange abilities

“The monster has a 25% chance to ignore magic.”

“The monster has a mind blast ability.”

These are some strange abilities that when adapting older modules for 5e don’t have an easy conversion.

You can say that if a monster has magic resistance just give them magic resistance. It makes the 10% magic resistance monsters more powerful, but it makes the 90% magic resistance monsters much weaker. You can to keep the old system or convert in these instances, but I would highly suggest converting to 5e magic resistance.

5e is much simpler, so many of the conversions will be simpler. There are some that you can’t make an easy conversion from.

Mind blast is a stupidly powerful ability. In 1st edition, if you didn’t have psionic defenses you were stunned for 1 minute. Now, if you fail you are stunned for 1 minute (can repeat the save every round) and take damage. In 5e the ability isn’t as strong since the recharge is on a 5-6. In 1st edition, the mind flayer can cast mind blast all day.

The general rule for adapting abilities is to make them less powerful.

I know that sounds weird, but some abilities are rediculous for even back then. If you are ever in doubt, make them less powerful by adding saves, possibly repeat saves and damage. Which is worse? Being stunned for 1 minute or being stunned for probably 1 round with a bit of damage?

The answer should be obvious.

But wait! We have not converted saves and AC yet!

AC and saves

Armor class is very different now. Back then better armor went down all the way to -10. That means if you convert the numbers the max AC anyone could have is 30. That actually isn’t a bad conversion. You can just flip the numbers and do some math. 0AC=20AC. -5AC=25AC. While 9AC=11.

AC is an easy conversion, but not everything is as easy when adapting older modules for 5e.

Saves are a pain to convert.

In AD&D when you leveled you gained a bit better save. Just like now right? Wrong. A save vs magic might be roll an 11 or higher to save vs every magical effect. Now we have constitution, wisdom, and every stat saving throw. When you get higher in 5e you get bigger numbers while the opposite in AD&D happens.

Here is the chart.

As you can see, when the level of a character gets higher the level of the save gets lower. That is why saves are not easily converted.

I suggest looking at the creature’s stat modifier and add proficiency.

So if a wizard was level 10 and had an 18 intelligence they add +8 to spell attacks and have a 16 spell save DC. The same thing applies to monsters.

But wait, now there are stats and to hit modifiers….

Stats and attack

Stats in AD&D were much harder to get and had a huge reward for the higher the stat you had. For example, an 18 gives +4 for us in 5e. For dexterity, this gave a +4 to ac as well, but strength gave anywhere from +1 to hit-+3 to hit and +2 damage-+6 damage. This seems odd but not too bad at first until you look at lower scores. What does a 14 get you in D&D 5e? +2. For AD&D you got nothing for any stat. 14 was too low to count, and 18 was the max.

This is why attack and stats are a little bit wonky. When adapting older modules for 5e keep this in mind and adjust stats accordingly. Our normal max is 20 with an augmented max of 24. For most monsters, you can adjust their scores +0, +1, or +2. For major villains adjust their scores up to +6.

HD was also the basis for attack in AD&D so try to make sure that the monsters are given appropriate attack values. You can do this by making their CRs as described above or by feel.

In short, you will be adjusting attack to be what you think it should be. Up to HD 6 or even 7 I just let it be that number unless I feel that it should be higher, but the higher up you get the more you should temper it. A 14 CR monster might only have a +10 to hit so be careful on how to adjust things. When in doubt, less is better.

(Surprisingly when looking at the AD&D monster manual the HD of monsters is very close to the attack bonus of many 5e monsters so it is a pretty good metric to go by.)

But lastly, we have damage to adjust


Did you know that in AD&D the only real way to heal was 1st level cure wounds? 1d8+0.

If you rested, you got 1hp per full day of rest. If you wanted another magical heal, it would be a 4th level spell for 2d8+0. This means that the main way to heal was through 1st level cure spells (2nd for druids) that healed at 1d8+0.

Because of this and most of the party never getting a constitution bonus (15 was needed for a +1) the damage was a little bit lighter. I emphasize the little bit part though since the game was trying to kill you.

That is why when you look at monster damage and try to convert it make the damage a little higher. If you can, add an extra element. Do not be shy. Make the monsters do something since this is not easy to convert.

A great example of this is the minotaur.

In 1 turn the minotaur in 5e can deal 10-48 damage (30 average) without critting. Do you know what a minotaur in AD&D can deal in 1 round without critting? 3-12 naturally OR with a weapon 5-20 vs a human. The damage is more than double for 5e.

If you think the damage is just double, then you are mistaken. An ice devil in AD&D does 7-32 damage. An ice devil in 5e does 21-47+30 cold damage for a total of 51-77 damage. I am no math expert, but that is a bit more than double.

What to do?

When in doubt

When in doubt about how to go about adapting older modules for 5e look up something that is their counterpart. We luckily have these monsters converted into 5e monsters, but you don’t always have that luxury.

Find what monsters are closest to the one you are converting and use those stats. Make something from those stats or just use those stats for the monster.

In short, you should be very proficient at making stuff up before you go about adapting older modules for 5e.

But we have not covered 1 topic still. Skill checks.

Skill checks

Some skill checks are pretty simple in AD&D. have a 1 in 6 chance to see a secret door. Have a 5% chance to find an item with a 15% chance to destroy the item. Have the players read your mind and do the thing or die/never progress.

Very simple, but not very adaptable.

In 5e a 1st level rogue is probably able to get a +8 with expertise on his best skills. At level 20, that rogue can at best have +17 with expertise and stats on his best skill. This is why 1 DC per level is a bad idea.

I would instead suggest going by the chart of difficulty for a trap found here.

This way you can adjust the difficulty of your trap, hidden door, or whatever by what you think it should be.


Adapting older modules for 5e D&D is a bit hard. You have a lot of factors to consider and adjust.

I have given you a framework for how to adjust certain aspects of the module. You are able to adapt some things cleanly, some with a bit of thinking and creativity, while others require gut feeling.

If you are ever in doubt, always make sure to make it easier than you think. You don’t want to be completely unfair to the players. That is unless what you want to adapt is the difficulty of an older module. In that case, go ahead and make your players experience the not so good old days when death was a common occurrence.

This has been Wizo and keep rolling!

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