D&D 3.x Using 3.0 Monster books in 3.5

[johnsemlak]

Are there any pitfalls in using a 3.0 monster book such as Tome of Horrors or Monsternomicon that I should be aware of when using them for 3.5?

 

[Gizzard]

I think that 3.5E made some significant changes to the way that PC parties play and that's going to affect all the monsters to some degree. Haste, Buff durations, Harm etc all changed and now expectations that were valid under 3E are no longer true.

There was a thread here just recently about the Immoth and whether it was overpowered for it's CR; I felt that it definitely was under 3.5E because its Ice Rune ability seemed to be a counter to the expectation that a 3E party would have Haste. It's things like that I am thinking of; if a monster is balanced to take on a Hasted party casting 4 spells a round then he's going to be overpowered when facing a party only casting 2 times. (Apparently he may be overpowered when facing a 3.0 party, but thats another story.... ;-)

Even at low levels things may have changed to make them more or less effective. A creature that depended on the Darkness-Blindfight combo is now hosed (Yes, I just ran into the new Darkness rules for the first time last night!) So I think you just end up looking at each new monster you are considering to see if his primary tactical ability got nerfed or pumped up under 3.5E in relation to what the PCs will be doing.

 

[Kae'Yoss]

Are there any pitfalls in using a 3.0 monster book such as Tome of Horrors or Monsternomicon that I should be aware of when using them for 3.5?

Basically, you can still use them. A lot of changes are cosmetical in nature - like the BAB/Grp line.
You'll have to change DR and Energy Resistances, though.
There may be pitfalls with specific monsters, but all in all you can do it. The way monsters acquire feats and skills has changed, but that's not that much of a problem.

 

[Li Shenron]

I think you can use them freely, but high DR such as 20/+5 becomes irrelevant once a simple +1 weapon can bypass it.

 

[Kae'Yoss]

I think you can use them freely, but high DR such as 20/+5 becomes irrelevant once a simple +1 weapon can bypass it.

Unless you change the type of DR. Not everything translates into /magic.

Look at the monsters in the MM to see what kinds of monsters have what kind of DR. Constructs get /adamantine, Devils /cold iron and Demons /silver (or was it vice versa?), fey get /cold iron, lycanthropes /silver. Some undead get /bludgeoning and creatures that are paragons of an alignment get the opposite alignment (celestials /evil, fiends /good, slaadi /lawful....)

 

[Li Shenron]

Unless you change the type of DR. Not everything translates into /magic.

I thought he was asking about using 3.0 monsters with 3.5 rules. If you change them, they are 3.0 monsters updated to 3.5 and of course it works better