Hi all,
I'm a little confused about Step 9 of the custom monster stats guidelines on page 277 of the DMG.
First it says "Giving a monster resistances and immunities to three or more damage types ... is like giving it extra hit points."
Then it says "If a monster has resistance or immunity to several damage types - especially bludgeoning, piercing, and slashing damage - and not all characters in the party possess the means to counteract that resistance or immunity, you need to take these defences into account ..."
So does that first bit mean that you only factor resistances and immunities into a monster's effective hit points if it has three or more of them? If it only has one or two, you don't worry about it?
If a monster has both resistances and immunities, do you multiply its hit points for both? So like if you have a CR 6 creature that has both resistance to fire and immunity to cold and poison, would you multiply its HP by 1.5 for its fire resistance and by 2 for its immunities?
Lastly, what exactly constitutes "the means to counteract that resistance or immunity"? If something has immunity to cold, for instance, as long as none of the PCs can deal only cold damage, it's not really an issue, is it?
Please help!
Thanks,
Jonathan
I just ignore the immunity part and assume the players will find a way around it (unless its immunity to B/P/S). B/P/S Resistances/Immunity I factor in, as per the little table. Other resistances I ignore when factoring, because there is usually an easy way around it.
If a monster was immune to all elemental damage, but not B/P/S I'd probably increase its effective HP by 25% assuming one caster, but there is always force damage....
In other words, I don't put much stock in resistances or immunities that are not B/P/S. They only effect casters, and the caster can't scorching ray, he'll lightning bolt instead, or magic missile, or acid splash, etc etc
Thanks. That's what I thought, but someone on EN World was telling me I had to factor them in, even if it's just cold and poison or something.
"the means to counteract that resistance or immunity"
If the caster has every L2 elemental spell (which normally would give him those 'means') but only one L2 slot, he doesn't have the means just now.
Make sure he has enough in-game and out-game information to realize that Element X will be a poor choice but Element Y / Z / W will be effective.
Sometimes it's blindingly obvious - the Balrog on the bridge ignores Fire attacks - but sometimes a Monster Knowledge check may be called for (hey, Wiz, do water elementals laugh at Ice attacks?).
Or maybe a wand with one charge left, Remove Elemental Resistance. (See if Wiz realizes that he can reverse-engineer the 'formula' to make this one. 
)