The hardest parts of Dragon Age, I've found, are the areas where massive amounts of bad guys take on your party of 4. My first play through, on normal. I played as a rouge & didn't get Morrigan cone of cold until almost the end of the magi tower. Suffice to say, that tower, with the desire demon's & their armies of templars, proved incredibly difficult.
2nd play through on difficult, went mage, & had no issues.
However on 2nd play through I'm using mods & those armies of archers are now quite tough with their AoE stuns.
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"The Rich are there to take all of the money & pay none of the taxes, the middle class is there to do all the work and pay all the taxes, and the poor are there to scare the crap out of the middle class." -George Carlin