3.5e Players, 4e GM

[Phaezen]

I have done something similar fairly successfully in Iron Heroes. The main trick is to look at the character bonuses to hit and damage output when designing your monsters.

Set ACs to require somewhere around 10 for an average fight and 13 - 15 for a difficult monster. Hitpoint wise I usualy try and make the fight last 5 to 10 rounds so budget on that. As for SLAs and Spells and feats use 4e like powers.

The big thing is to be honest with your players beforehand that you are not going to be using the 3.x system for creating monsters, if they are happy with it spend some time experimenting till you find the sweet spot and from there, have fun.

 

[StreamOfTheSky]

The math would be so off, it wouldn't even be funny.

Let's take a lv 14 4e monster. It's attack against a NAD would be around +18. Translated into 3.5, that would be around a 28 or 29 DC. It's NADs would be around 26, so it would be translated to around +15 or +16 to saves.

edit: That's not even counting the fact that the power level in two systems scales in totally different ways. A lv 14 4e monster is not a CR 14 monster. A lv 20 3.5 wizard >> lv 30 4e wizard.

And yet, those Save DCs and save bonuses look really, really good for level 14, even though a "CR" 14 4e monster is probably weaker than a 3E CR 14 monster, looks like some of its numbers would actually need reducing, too. Especially since in 3E it would likely be an even lower CR. I don't care how much people harrange broken casters.... I have powergamed lots of them, and getting a DC 25 by level 14 on your highest spell levels, never mind the lower ones, is pretty decent. DC 28 would likewise be very hard for someone with a bad save, and fair to easy for someone with a high save (cleric on a will save, good base + high stat, for example). I concur...math nightmare.

 

[Trihelios]

I'm curious, why would you want to do that?

Either 3 or 4 work fine on their own, if you like the monsters from 4th you could surely convert them into 3rd edition monsters. There are instructions in the back of the MM on inventing new monsters, just take the ideas of the 4th edition monsters you like and build them as 3rd edition monsters.

 

[ronin]

I think the thing that has made 3.5 easier to run for me was to stop handing out XP. It allows me to use whatever I'd like to challenge the party without worrying about calculating how much XP they'll get for overcoming the encounter. Now if I want to modify a creature I'll just add whatever ability I'd like for it to have without regards to modifying the creatures CR at all.

I wish I would have started this practice a few years ago.

 

[Charwoman Gene]

I have done something similar fairly successfully in Iron Heroes. The main trick is to look at the character bonuses to hit and damage output when designing your monsters. *snip*

This is more along the lines of what I;m ultimately doing. I'm trying to work out a way to improvise monsters with some guidance.

 

[Voadam]

This is more along the lines of what I;m ultimately doing. I'm trying to work out a way to improvise monsters with some guidance.

I'd suggest using the chart from the Pathfinder srd monster creation stats page as a base for stats then adjust for monster role as given in the 4e DMG.

Most 4e monster powers will work fine in 3e, save ends works as a 3e mechanic, recharge power rolls work as a mechanic, pushing, pulling, sliding, shifting etc. can work in 3e.

The math for save DCs and defenses as well as hp and damage I expect to be the biggest discrepancy in compatibility for the two based on the different math. I'd suggest going with the pathfinder math here as your baseline instead of 4e.

 

[Janx]

I think the thing that has made 3.5 easier to run for me was to stop handing out XP. It allows me to use whatever I'd like to challenge the party without worrying about calculating how much XP they'll get for overcoming the encounter. Now if I want to modify a creature I'll just add whatever ability I'd like for it to have without regards to modifying the creatures CR at all.

I wish I would have started this practice a few years ago.

I don't think this has anything to do with the OP's question. XP comes at the end. The encounter comes first. How much XP it is worth doesn't matter.

When we started 2e, we used 1e MMs. It worked fine. But then the rules still had the same metrics. AC, HP, THAC0 and damage were all discernable from the MM entry. Heck, that stuff would still work in 3e (the biggest flip being AC and THAC0, but it's adjusted by simple math).

4e sounds like it has totally different values. What's a NAD, for instance?

If monster's still have a to-hit, AC, HP and damage, you'd be mostly OK. But if there's too many differencesl, it's probablly not going to work. In which case, take the 4e ideas, and apply them to 3e, but not the literal rules.

 

[hexgrid]

I'm curious, why would you want to do that?

I can see the appeal- if the players really like 3e character creation, but the DM really likes the way monsters work in 4e.

 

[Voadam]

I don't think this has anything to do with the OP's question. XP comes at the end. The encounter comes first. How much XP it is worth doesn't matter.

When we started 2e, we used 1e MMs. It worked fine. But then the rules still had the same metrics. AC, HP, THAC0 and damage were all discernable from the MM entry. Heck, that stuff would still work in 3e (the biggest flip being AC and THAC0, but it's adjusted by simple math).

4e sounds like it has totally different values. What's a NAD, for instance?

If monster's still have a to-hit, AC, HP and damage, you'd be mostly OK. But if there's too many differencesl, it's probablly not going to work. In which case, take the 4e ideas, and apply them to 3e, but not the literal rules.

There is a significant difference in math numbers between 4e and 3e, it would be a lot more like going from 3e to 1e than 2e to 1e. 1st level 4e kobold monsters have over 20 hp for example. AC and all defenses and attacks go up 1 every two levels, there are no iterative or multiple attacks, and damage is generally lower and less swingy in 4e than in 3e.

Also 4e monster level is not quite the same thing as 3e CR. One party level CR monster is designed as a baseline challenge for four 3e characters while five party level monsters are designed as the baseline challenge for five 4e characters.

 

[StreamOfTheSky]

4e sounds like it has totally different values. What's a NAD, for instance?

Non-armor defense, iirc. Those would be reflex, fortitude, and will, which in 3E are saves and in 4E were inverted to be defenses the PCs rolled against, like AC. I prefer them as saves.


I still think it'd be easier ot just do an educated bs job than try to convert between 3E and 4E. Just give monsters attack and saves bonuses and AC that looks right compared to the party (some higher/lower than others, depending on what type of enemy they are, but always within a fair "success" range) and incorporate 4E ideas like monsters playing by different rules than the PCs. Give them max ranks in x + int (depending on race/class) skills that are most useful, and so on...

Just seems like a much easier way to achieve the same thing to me.