@ginnyfizz:
This worked for me on normal, hard and Nightmare. (all classes, but mage is hardest).
Aveline is your tank, but she can't stand being swamped with darkspawns, so you need to get them off her. Also she is stronger/harder than you, so you won't be able to easily survive standing besides the ogre, even if she is tanking, due to the AOE, so focus Bethany/Carver and you on killing the smaller darkspawns.
This works well on normal or hard, and Aveline tanks the Ogre on her own, while Carver/you and Bethany/you deal with the riff raff and once they are done you all focus on the Ogre (remember to use shield defence on Aveline).
If you are still struggling, as I did on nightmare to keep Aveline alive: Pull her off the ogre and have her help killing smaller spawns as well, as long as who ever got the aggro from the Ogre keeps her/his distance - this is probably the easiest road. Here the Mage in my nightmare runs attacks first and hardest, gaining a strong aggro from the Ogre, and then just runs in circles while throwing ice, and sometimes fire (watch for FF on Nightmare). It turns out that doing this will actually make the Ogre really easy as it will continue to rush you, and throw rocks; but since Nightmare brings FF for everyone the ogre will injure his friends more than he ever does your mage (Avline and Carver/you can withstand her rushes decently).
Actually I once lost both Carver and Aveline on the Ogre, only having my mage, and mindblast (tried a non fire solution) - and its possible to kill all spawns and the Ogre with just mindblast and the staff; just keep kiting them, and once they get too close (can't be too often) use mindblast. Takes forever, but is doable since nothing there is using arrows, save the Ogres rocks, but they can be easily sidestepped.
& as Thandal wrote remember to use your talents - and remember to use your natural (extremely potent) health regeneration - just 10 seconds off the mêlée and you can dive back in again; use this if possible instead of potions (that are only a last resort, though do use them since they will vanish after this fight anyway).
Also this is for the final Ogre fight - for the first I'd just use the abilities you have and if need be back off (or if rogue use evasion) once health is getting low. Hard to help on this one since I never had any issues here.
Edited by randName, 06 March 2011 - 06:27 AM.