Dragon Age: Origins Walkthrough - The Sacred Ashes of Andraste - The Mountain Top and the Dragon
The high dragon in the Ruined Temple at Haven is one of the toughest enemies in the game. Killing this beast will net you a dragon scale though, which will let you craft some of the best armor in the game. If you need any help killing this beast, then look here.
Did you see the big dragon in that video? Well, you don't have to fight it. You actually need to draw it into a fight, since it isn't in a place where it will attack you. The bonus is that if you kill it you'll have a dragon scale for Wade to make into really good armor. On the PC version, you have to go into your inventory and find Kolgrim's Horn. You also need to have killed Kolgrim obviously. Then right-click it and “Use" it to play the horn. I believe that console players need to use the gong on the mountain top. The high dragon will come down and attack you. Note that it will land right on top of you if it can. I suggest that you have the ranged fighters fall back and hold their position. Then have the tank run out to trigger the attack. Run away and wait for it to land, then move in and attack.
I can say definitely that it will crush a level ten-twelve party like mine, so we're going to skip it for the time being (at least if you're following the order of my guide). If you don't want to fight it, go straight through to The Gauntlet. I still had a bit of trouble doing it with level fifteen characters who had just breezed through Orzammar, so keep that in mind.
Fighting the High Dragon
There isn't too much of a trick to actually killing the Dragon. You definitely need a mage or two with some healing abilities. Melee isn't going to be very effective. You can make it work with a good healer, but it's going to be a really slow grind. Ideally you could make due with your mages and archers dishing out the damage while one tank distracts the dragon. Naturally you should do what you can to make this tank fire resistant.
Rogues are worthless for flanking or backstabbing. In fact, this is a rare time where you really need to attack something from the front. It can kick at anyone standing behind it and usually score a knockdown.
You can't really freeze or stop it for long. The most useful magic will be a few hexes. A vulnerability hex or even a misdirection hex will do wonders for setting it back a bit. That type of magic tends to work pretty well too.
The dragon has a few special attacks. It can sweep at the people in front or behind it. This will usually knock them down and back. It can also breathe fire on anyone near it. Be sure to keep your ranged fighters at a distance to avoid this. The worst attack is that it can grab someone and smash them to death. If it does this, then you'll need to do something to stun it. Hitting it with Earthfist usually works.
If you can manage to stay alive and break it's grip attack, then you can probably make it. Just keep popping potions and have your ranged fighters hang back.
You can do this with a melee group if you want. In fact, I did it. I know that it is at least possible, since I just didn't have good ranged builds ready. Like I said, it's just a long grind and you'll need to do a few revivals and a whole lot of healing. It should finally die after a long fight.
There isn't much else to do. Make sure that you search its body for a lot of loot and a dragon scale. You can take this scale to Wade at Wade's Emporium and he'll be able to craft together some good armor. I suggest that you get a few drake scale sets though, since he'll be able to make a better set of dragon armor if he has some experience.