On my first playthrough I burnt all my lyrium potions during the Revenant battle in the Mage tower (level 7/:) and eventually I had to do the End boss of that level without any potions at all... without Force Field & Cone of Cold, it would probably have been impossible to win.
I was lucky that I had just continued developing the spells Morrigan started out with, instead of giving her fire spells...
Brecilian Forest first, without Wynne? There are some very challenging fights there for a low-level party.
I'd take Circle Tower, followed by Redcliffe-Denerim, then Elves, Urn & Orzammar.
Huh.
First time I did Battle of Redcliffe, militia got wiped out. Second time... same result. It's best to leave Redcliffe before the battle, and leave the schmucks to their fate, imo. Same difference.
Cone of Cold still owns almost everything on normal, especially after a Vulnerability hex.
I figure Misdirection hex later in the game makes Revenants (and any other heavy hitting mini-boss) cake.
But on Hard/Nightmare most critters probably have ridiculous resistances against everything. Bio's idea of making a game hard.
The endgame boss should've been a giant Darkspawn version of Cauthrien dual-wielding Summer swords. That would've been epic.
On the third level, there's a broken statue with a black phylactery, IIRC.
Enemy mage AI is retarded. Most threatening thing they do is throwing a Fireball when their own allies are attacking your party... and occasionally an Emissary will use Crushing prison or Curse of mortality, which is easily dispelled by Cleanse Area.
But considering how overpowered mages are, it's maybe for the best. A lone mage with decent AI would easily tear apart any party... and it's no coincidence enemy mages don't use mana clash either.
The only decent mage I've encountered is Mr Teleport in the Elven Ruins. At least he would use Paralyze when you'd try to bull-rush him.