another stupidly difficult fight that I had was the alpine dragon. tough guys such as Pallegina, Zahua and my watcher were massacred super fast, High damage dealers such as Aloth and Zahua attacks were not effective against this demon. I eventually killed him but I had to use very high Fire damage attacks, my paladin was effective here and also durance.
Confusing does wonders here, using the dragon's minions as shields in a sense. Keep them alive long enough to finish the dragon. BTW Having Steadfast fully evolved helps a lot too (that's true of any Dragon fight, really).
The way I killed it was by putting Zahua and Eder to the front so they can distract the beast... My paladin watcher was killing every minion possible, Durance buffed the tanks and also had the rain of fire and cleansing flames to attack the dragon directly. Aloth with the magical spear was helping the watcher to kill the minions and Pallegina buffed the watcher and Aloth with + 25 deflection bonus. when all the minions where slaughtered by the watcher an Aloth, this last one buffed himself to the top and started casting pierce and raw damage spells while the watcher did the sacred immolation that dealt damage to the dragon while healed my other people which were fighting the beast. Zahua had his clones invoked to help and he was using a spear plus resolution sabre.