How do you determain challenges?

[Majoru Oakheart]

But here's the really interesting thing I've noticed: some of my players who began with 3E and have only experienced the game with a CR system will actually calculate the CR of an encounter in the middle of the encounter, and if it's "too high," they'll start complaining about the inevitable TPK that's coming, even though they're winning the fight. They're so sure they can't win, in fact, that they start looking for escape routes, or going on total defense when they should be full attacking...and it becomes a self-fulfilling prophecy!

I've seen this happen as well. Then again, I've seen a DM who threw out the CR system entirely and threw an EL 28 or so encounter against us while we were 7th level. We were massacred. We all saw it coming, but there was nothing we could do. He thought it was a valid challenge.

The problem was that CR wasn't accurate enough and power varied too drastically from character to character. A group of really power gamed characters with good equipment could fight 2 monsters who were BOTH CR=(Average Party level)+4 with not much of a problem at all. Even though that is officially an EL+APL+6 Encounter, which means it should TPK all groups without fail.

On the other hand, the XP system from 4e is much, much more accurate. Throw a group of 5 level 6 monsters up against level 1 characters and you can pretty much guarantee a TPK.

 

[Belphanior]

But here's the really interesting thing I've noticed: some of my players who began with 3E and have only experienced the game with a CR system will actually calculate the CR of an encounter in the middle of the encounter, and if it's "too high," they'll start complaining about the inevitable TPK that's coming, even though they're winning the fight. They're so sure they can't win, in fact, that they start looking for escape routes, or going on total defense when they should be full attacking...and it becomes a self-fulfilling prophecy!

I began with 2e, and even I've done that twice now. Of course, the DM in question sent a group at us with an xp budget five times what was supposed to be used. Both times. And I do mean "sent at us", it's not like we willingly sought out a nest of black dragons at level 2...

As a result, both encounters were played as if we were facing drooling morons without any tactical talent or half their powers. Not very satisfying at all. With a DM pulling his punches like that you just don't feel like you've just slain a dragon, just a big pile of hit points.

Anyway, point here is the xp budget can fulfill a very useful role in constructing encounters. Players second-guessing the DM all the time can be jarring, but the flipside of that coin is that some encounters are so obviously out of whack that a player can't help but wonder just how screwed up this fight is.

 

[bouncyhead]

some of my players who began with 3E and have only experienced the game with a CR system will actually calculate the CR of an encounter in the middle of the encounter, and if it's "too high," they'll start complaining about the inevitable TPK that's coming, even though they're winning the fight....
I think I hate the concept of challenge ratings (in any edition).

And conversely, players weaned on CR's or XP budgets live in a world in which every challenge they encounter (be it a combat, a steep cliff or a trapped portal) has to be 'do-able' because they know the DM is working within guidelines. That makes life far too comfortable. For me, I like the idea that there are some challenges that (fair warning given) the party only mess with at their peril.

 

[Jhaelen]

And conversely, players weaned on CR's or XP budgets live in a world in which every challenge they encounter (be it a combat, a steep cliff or a trapped portal) has to be 'do-able' because they know the DM is working within guidelines.

Except that if the DM is following the guidelines from the 3E DMG, 5% of the encounters will have an EL of 5 or more higher than the effective party level and are NOT supposed to be doable.

To the OP: The 3E CR system worked well enough about 90% of the time. It's the 10% that cause worries. The 4E XP budget system seems to work a bit better, say 95% of the time. That still leaves a lot of encounters for which it doesn't work well.

Anyway, both systems serve as a good starting point for judging how hard an encounter will be. If the DM has a good idea about what the party is capable of and where their strengths and weaknesses lie, she should be able to adjust encounters to get about a 99% certainty. It's of course impossible to account for (bad) luck or exceptionally bad/good tactics.

Calculating DPR, however, is a very limited concept that doesn't really work well outside of CRPGs. It can be a useful tool to optimize solitary characters but not much more. It ignores both synergies within the party and their opponents and movement/terrain features.