This page will give some tips and advice on converting monsters from previous editions of D&D to 4e.
3e/3.5e/Pathfinder to 4eEdit
This section will provide an example for converting a 3rd edition era monster to 4e. For this example, I will use a monster that is needed for an adventure I am converting. The Vargouille. You can view its third edition stats by viewing its page in the Hypertext D20 SRD. The Dungeon Master's Guide has information on designing monsters on pages 184-185 which should be referenced. Keep in mind that monster damage and their hit points, attack bonuses, etc. got changed in the July 2010 Updates. You can find the updates on the Official D&D Updates page.
Step 1: LevelEdit
First thing to do is determine what level and role the monster will play. Keep in mind that it is quite possible that this will change as you go. Also consider the differences between the editions. In 3rd edition, a monster was a singular monster. In 4th edition, monsters have roles, so you typically see more than one version of a monster so that all, or at least some, of the roles are filled. You may be able to fit a monster nicely into one role and it's sometimes its powers will suggest multiple roles. We'll get a bit more into this later.
In estimating a level, the first thing to look at is it's Challenge Rating. This provides a good starting point, however we have to remember that 3rd edition was built around a 20-level career whereas 4th edition is built around a 30-level career and monsters have to comply as well so you have enough critters to fight over your career. A 10th-level 3e character is equivalent to a 15th-level 4e character in terms of where they are in their career and relative power. As such a CR 10 creature could easily be looked at as a level 15 creature in 4e since it's meant to challenge players of that relative level. In such cases, you would multiply the CR by 1.5 to achieve the relative 4e level. Where this breaks down is on low level creatures. The Vargouille, for example, is CR 2. We can make a 3rd level creature in 4e by multiplying the CR by 1.5. In this case we may not want to. Although the difference in level between 2 and 3 is slight.
One other thing to consider when determining the converted level is the average hit points, although we have to remember that the number of hit points between 3rd and 4th edition are significant. Hit points are higher in 4th edition than they were in 3rd. As such you should only use the average hitpoints as a guideline to refine your relative level. As an example, the Vargouille, a CR 2 creature, has 5 hp. A level 2 skirmisher in 4th edition averages about 36.5 hp. That's a seven fold increase!
The Vargouille in 3e was a CR 2, 1 Hit Die creature with 5 hp. So obviously it's a low level creature. Going by it's CR we may want to place it as a level 2 creature. We can start there for now and tweak it as we see fit.
Step 2: RoleEdit
Determining role can be done through the use of the monster's fluff and by looking at its abilities. Seeing as we're going off the SRD entry for the Vargouille, we're a bit short on fluff. However, we can look at its special attacks which are: Shriek, Kiss, and Poison.
- Shriek allows the Vargouille to affect anyone within 60-ft. with a fear attack that paralyzes the victim. This sounds rather controller-like. So that may be a good choice.
- Kiss allows the Vargouille to attack a paralyzed victim and infect them so they become a Vargouille in 24 hours. 4e did away with a lot of these save or die (in this case a slow death) type attacks, so it's unlikely that this would stay in its original form for the converted creature. However, its another controller-like ability. Another way to look at it would be that it's good for a different role. Maybe a lurker or skirmisher. Once the controller Vargouille paralyzed a victim, the other one comes in and performs a Kiss.
- Poison just means all its attacks inflict poison damage. Nothing too role specific there.
So on first glance, it would seem that Controller would be a good role for the creature. However, if we look at its skills in 3e, we see that it has a +11 Hide and +7 Move Silently. It also has the Stealthy Feat. So it looks as if the Vargouille likes to hide and wait for prey then attack. This fits the lurker role, and one could argue the skirmisher role.
As we look at it, it would seem its tactics may be best served to paralyze victims with a Shriek then dart in to bite them with their poisoned attacks. We're already seeing how we could split this into more than one creature. A Controller that paralyzes and a lurker/skirmisher that darts in and attacks the affected enemies. For the sake of the example, lets just stick to one role. Since the Shriek seems to be its big attack, we'll put it in the controller role. This will determine its hit points which will be 38.
Step 3: Size, Origin, and TypeEdit
In 3e a Vargouille was a Small Outsider (Evil, Extraplanar). So Size is easy: Small. Origins in 4e differ from 3e since the cosmology is different. Without the fluff, we'll have to rely on other things to get a picture of what it should be. In the Vargouille entry in the SRD we see that they speak Infernal. In 3e we had the Infernal and Abyssal languages which were spoken by Devils and Demons respectively. Since it's an Outsider and speaks Infernal, we can extrapolate that Vargouilles must originate in the Nine Hells. In 4e, the Nine Hells are in the Astral Sea which would classify the Vargouille as an Immortal. Types also differ in 4e in that there are fewer of them. In the Vargouille's case, it fits the Type of Magical Beast. So in 4e it will be a Small Immortal Magical Beast.
Step 4: Ability ScoresEdit
In 3e the Vargouille's ability scores were: STR 10 DEX 13 CON 12 INT 5 WIS 12 CHA 8. In 4e monster design we need to look at the scores in pairs. STR/CON, DEX/INT, WIS/CHA. The best score in the pair averages 10 + 1/2 it's level, so in the case of the Vargouille it's 11. It's primary attack stat will be 3 higher. The Shriek ability in 3e was based off Constitution, and CON was the highest ability score, so we'll go with CON being the base stat for attacking. So it will be a 14. The rest can be adjusted as you see fit. I'm more than happy to go with the stat spread from 3e. So our 4e scores are the same except for CON which is 14.
Step 5: AttacksEdit
- The main attack of a Vargouille is a bite. So that's easy enough. The original did an extra 1d4 poison damage. The normal damage for a creature in this level range is 1d8 + 5, but it's also low level and we're going to add in poison damage so we should go with the low damage scale for it. So we'll make the bite a melee attack that does 1d6 + 4 and ongoing 5 poison damage (save ends). It will also be its basic melee attack.
- The Shriek is its big control attack. The original description makes it like a Close Burst attack, however I think in this case it should be done as a Close Blast because it seems better as a targeted/directed attack. The original affected anything within 60 feet which is a huge area! I don't think a Close Blast 12 (or Close Burst 12) is going to make anyone happy. A Blast 3 will cover 9 squares and a Blast 4 will cover 16. Since it's low level, we'll go with the Close Blast 3. Since we will stay with the idea of the Kiss being used on an enemy affected by the shriek, it should probably be a recharge power. Also, we have to consider if we're facing more than one of these, how would it play out with multiple Vargouilles constantly recharging and re-paralyzing the players? A recharge of 5-6 should do here. As a single creature it's likely to not be of much use, but in a group they become more dangerous. Since this affects multiple targets, we shoudl go with the low damage scale again. In 4e total paralysis would be the helpless condition which would be a bit powerful for a level 2 creature. As such, the next best candidate for a low level creature would be to immobilize the victim. With the recharge possibilities of a group of Vargouilles and their Kiss attack, it's probably best to have it end at the end of their next turn. So we'll have a Close Blast 3 attack that attacks Will (and we'll give it the Fear keyword), deals 1d6 + 4 damage on a hit and immobilizes until the end of their next turn.
- The Kiss attack. Since the original attack basically killed its target in 24 hours (or sooner) if a save was failed, it's not suited to 4e, but we want to include it. You could do it up as a disease, but that's a bit more involved than we want to deal with here. So the best solution is to make it an attack it can do against an immobilized creature. Since it's more limited in its use, and may well only be able to be used once in an encounter if Shriek never recharges, we'll treat it as a limited use ability for its damage expression. Since it's restricted in when it can be used, we can leave it as an At-Will attack without worrying that it may be overpowering. Since it is in effect a bite attack, it should also deal ongoing poison damage. So in the Monster Builder, we'll use the Limited Use boost to damage, and also make the damage Low. So it's an attack against AC that does 2d8 + 5 damage and ongoing 5 poison damge (save ends).
So that rounds out its powers. At first glance three attacks may seem to be a lot for a level 2 creature, however it's unlikely to use its regular bite attack unless it's forced to make basic attacks. Already we can see the tactics would be best where the Vargouilles hide, one comes out and targets as many enemies as possible with a Shriek and then the rest swarm in and use their Kiss on the Immobilized victims. Once that wears off another one shrieks and so on.
Step 6: Additional DetailsEdit
- Skills: Most 4e monsters have few trained skills. Most of this will fall under the "Additional Details" of monster design as outlined in the Dungeon master's Guide on page 184. For the purposes of the Vargouille, we saw that it was stealthy, so making it trained in Stealth is a good idea. Since it likes to hide than attack, it may want a good perception to detect prey. So we'll give it training in perception.
- Alignment: The old Vargouille was always neutral evil. That doesn't exist in 4e so we'll just make it evil.
- Senses: The original had Darkvision, so we should give it to the new version as well.
- Movement: Vargouilles can fly 6 squares. In 3e they had Good flight which means they could hover, so we'll give it the hover capability on its flight. It has small appendages, but it isn't suited to ground movement, so we'll restrict it to movement 2 on the ground in the off chance it becomes grounded.
- Languages: Infernal doesn't exist anymore, but since they hail from the Astral Sea, we can give them Supernal.
So that's pretty much it. We have our 4e Vargouille. Plugging it all into the Monster Builder we get the stat block:
2e to 4eEdit