What exactly does Challenge Rating mean? I’ve always been under the impression that it’s supposed to represent the approximate level an average party of four characters would have to be in order to kill a given monster. From general observation, however, parties seem to have no trouble taking down creatures that are a good 2-3 challenge ratings higher than their level.
Of course, every rule has its exceptions and there are few monsters that come to mind when I think of things that have caused an unexpectedly enormous amount of trouble for an encounter of their level. At the top of this list are Bodaks, Nightwings, and Bleak Born (Coincidence that they’re all undead? Probably not!).
To use a real game example, I’ve been playing for years in a game run by Opinicus. We are level 16 and our party consists of me (a fighter-rogue-Master of Chains, lots of attacks, so a large amount of cumulative damage per round, but not too much per hit), a paladin (not as many attacks, but as ton of damage against anything evil), and a Ranger-Scout-Deep Woods Sniper (given enough of the right magical arrows, she basically fills the roll of an evoker). While the other two can use divine items and I have enough ranks in Use Magic Device to activate most other wands, staves, and scrolls, you may notice the lack of a full time spellcaster. In order to make up for this, Opinicus has been more than generous with magic items, but when the chips are down, there really isn’t a way to compensate for the versatility of a full caster.
Getting back to the example, in a recent adventure, our party was doing the whole on-a-boat-on-the-Astral-Plane thing when our ship got jumped by a bunch of greater shadows and Nightwings. Now, in a previous adventure, we had just taken down a dracolich (given, it was slightly powered down, but come on, we’re level 16, it’s CR 23), so you would think taking down two CR 14 monsters and some minions would be a somewhat challenging piece of cake.
Now the shadows were alright, largely. As long as we had initiative on them, we could pretty well level one each in one round if we rolled well on the miss chances. The Nightwings, on the other hand, were a horse of a different color. Even ignoring all spell like/supernatural abilities, they can still drain magic items, and ignoring their ability to drain magic items, they spend their time flying!
Seriously though, I’m not just writing this to complain. About two rounds in, Opinicus just kind of looked at us and admitted that the monster was totally out of balance. Mind you, the initial reasons why he chose the monster made sense: it was a CR 14 extraplanar undead.
The fact that it was only considered to be a proper encounter for a 14th level party is what really got me thinking. What do the books assume a party consists of? Is it assumed that a party is just four random characters of any class, either different or the same, or it is assumed that the players have put thought into having a balanced and efficient party.
Of course, given the nature of D&D and high fantasy, it stands to reason that a balanced party would contain at least one full time arcane or divine spellcaster (if not one of each).