In our present campaign, we fight a lot of demons. This is what our paty has found:
Rule #1: Demons are just as vulnerable to sneak attacks as everyone else. Make sure that you've got enough light sources to counteract their darkness abilities in order to maximize the number of times your rogue can lay the sneak attack down.
Rule #2: Mages don't tend to fare well against demons. This is especially true for "boom" mages that rely overmuch on energy attacks. In a fight with demons, mages are more effective buffers than boomers.
Rule #3: Demons dish out tremendous amounts of damage, but generally take a lot of attacks to do so - DR, therefore, is your friend. Stoneskin is the protection of choice for fighting demons. Addendum: Demons will outdamage your front line fighter, so make sure your fighter had a friend. That way the fighter's partner can (maybe) take some of the heat, and more importantly can lay some smack of his own.
Rule #4: When fighting demons your cleric is not a fighter in priests clothing. She is instead a healer and buffer, and will almost assuredly be spending every round undoing the damage donw by the demon. Maybe your cleric will be able to stand at the front line in other fights, but demons are a different story.
In general, if a PC trades full attacks with a demon or nearly equal CR, that PC will lose. This is even true for our demon killing machine (a rogue/ranger/Foe Hunter that can toss double handfuls of dice on a moderately successful attack against demons). Our usual tactic is to remove their ability to flee (anchoring them), get them on the ground (by grappling them if necessary - all it takes is one opposed roll going our way), and surround them while our mystic theurge casts healing spell after healing spell through his spectral hand. Even with DR getting in the way, the nastiest of them only last a handful of rounds.
![:]](http://www.enworld.org/forum/images/smilies/devious.png "Devious :]")
