FrankTrollman at [unixtime wrote:1090538931[/unixtime]]
If the party beats the monster without cost because they have immunities, then the fight required the expenditure of resources - the cost of gaining the immunities that won you the encounter.
This assumes the resources are expendable. In most cases, they aren't. Simply taking a level of a PrC that gives you full immunity isn't an expendable resource, its a choice you made and now you've got it. Handing out XP for it is like handing out XP to a fighter who hacks down a wall, because he expended resources gaining the ability to bring up his damage to that level.
It may not seem like it cost you anything now, but it costs every single adventure in every fight you ever have. It costs however much it cost to get the immunities.
You're saying apparently that by taking a level in something you're expending resources? Your logic is screwy on this one.
The battle has to drain your resources in some way... and you can't drain away a permanent ability. Gaining maximum hit points isn't expending resources, nor is gaining another spell slot, only when I actually spend them am I expending resources. If I was only immune to X number of attacks per day, then I'd be spending resources, but total immunity means you spend nothing.
If you throw a DM temper tantrum every time the players' special abilities which they paid for actually pay off, you are only discouraging characters from getting interesting or conditional abilties. I mean, you don't give people a small proportional XP reduction in every single encounter when they take a strength buff instead, do you?
I'm saying that superconditional abilities like that shouldn't exist at all.
What fun is it to have an encounter where the mosnters can't touch the PCs? This isnt' a strategy game, the ability to totally rape one thing in exchange for being supposedly weaker against everything else shouldn't even be allowed in an RPG, because you've got to stick to the same character all along, and allowing a PC to make trades like that is bad for the game as a whole.
The thing is that quests aren't made typically on the basis of a generic party. More often than not, you make them for your specific PC party, and you tailor the quest to the group. The DM is not going to throw in a trivial encounter that the PCs get full experience for with no risk, unless he feels like playing santa claus. Nor is he going to throw a group of monsters at the PCs that will deliberately destroy them by preying on their weaknesses.
It's entirely possible to find a counter for any group of characters and totally wreck them, but that's not the point of the game. The point is to make something reasonably challenging and go with it.
An ability that potentially removes all the challenge from an encounter is counterproductive. As a DM you probably aren't going to bother putting the encounter in the game, and as a player you dont' really feel much satisfaction in it either, unless you're one of those cheese gamers who is going to make every attempt to try to rout packs of shadows to gain free XP.
But presumably most gamers play the game to actually encounter some sort of challenge and feel some degree of fulfilment from overcoming it. I mean granted there are people who just love playing 20th level characters in quests designed for 1st level characters, these are the same people who will spend endless hours playing thier favorite first person shooter in god mode too... but this isn't the usual kind of person you get in your game. Usually if you throw a bunch fo trivial crap at someone they're wondering why you're wasting their time rolling for the battle.