May contain spoilers. No names or storyline, but it does contain my strategy to clearing a dungeon.
I just did the first dungeon in Denerim. Holy shit did the difficulty ramp up. I made it 1/2 way to the dungeon when I hit a fucking big wall. Had to fight 2 reg guards, a bulk guard, a capt., and two reg mages... All while on fire due to setting a trap! After dying 4-5 times, I ended up switching it to easy. Even then the enemies were tough.
The boss fight was pretty hard as well, even on easy. I had to keep frost cone on the boss at all times, all while fighting another mob. My 3rd cone missed and I thought I was screwed, but luckily my other 3 characters had finished off the 2 melee mobs that they were fighting. They came to my rescue and the fight was much more manageable with only the boss to worry about(had killed the other mob).
Fair warning to everyone just getting started... make sure you either have a high level herbalist who can make tier 2+ health potions(Morrigan starts off at lvl 2 herb I believe), a magic healer, or a lot of health potions. Denerim is the first major place I went to after given the choice, and the quantity of health potions is pretty dry. I've been lucky enough to survive with <5 potions, but it was pretty hard and I had a lot of wipes.
Also, I would suggest having a gambit that auto heals to the lesser health potion in your bag when your characters are below 25% or 10%. That shit will save your life!
Edit-For anyone going with Morrigan in your party, make sure you get the frost cone spell as soon as you level. It wil freeze all persons in its path(even friendlies) for 15+ seconds. It's so far the best CC early in the game. It can even freeze bosses and their doesn't seem to be diminishing returns(or at least I haven't seen it miss yet). Only downer is that it'll freeze your party members if they're in the way.