You can finish the game on Nightmare in 3 to 4 hours, including loading time, if you are willing to do some glitching. Explained here:
https://forum.speedd...inquistion.htmlEven if you don't want to glitch, there is great advice in that thread on the sequence of quests and agents to acquire to minimize the amount of time running around gathering Power and Influence. Using that advice, I was able to get everything needed to start Champions of the Just in about an hour, from a new game start.
BTW, Champions of the Just is the faster of the two quests to complete -- you can run through most of the Fade part without listening to all the dialogue, so side with the Templars. This also makes the battle at the Well of Sorrows a bit easier.
As for class/specialization, the speed run guys all used a mage with no specialization, because doing the specialization quest takes time. Mage is good because Fade Step speeds up travel and there are plenty of non-specialization abilities for damage and protection.
Archer is also good -- the Envy demon battle is much easier with an archer vs. a mage. Any Archer specialization is good. I'd personally go Assassin since you can Stealth sneak past anything that would waste time. You could do that with any Archer, but you get more benefits from Stealth for an Assassin.
For party composition, if you are playing a mage, I'd go Cass for tank -- unless you are willing to go back to the Hinterlands to get Blackwall -- Solas and Varric. I'd swap in Cole (spec'd for Archer) for Varric as soon as you can, unless you are willing to spend time upgrading Bianca. It's kind of a wash, since no matter what rogue you take, you have to spend time upgrading their gear. I just find it easier to upgrade bows over Bianca, particularly with the Golden Nug providing all the best schematics. On the other hand, the AI does a slightly better job with Varric over Cole as an archer -- AI can't be trusted to use MoD correctly -- so I guess it doesn't matter.
If you playing an Archer, swap Dorian for Varric as soon as you get him.
For builds, I prefer mages to be all Inferno or all Winter for combat, with a little Spirit and then their specialization skills. From Storm, Energy Barrage and some passives are good. You can also go for Static Cage if you want, but I find Storm combat abilities relative weak, compared to Inferno and Winter.
Archer builds should go: Long Shot, First Blood, Explosive Shot, Pincushion, Death from Above, Leaping Shot. Then whatever else you want, including specialization. Point is, get Pincushion as soon as possible.
For tank, whatever you want. Hard to build Cass badly. That said, if you switch her to 2H, definitely get Flow of Battle as soon as possible and craft for crit. For 2H I like Pommel Strike and Whirlwind. For S&S I like the left hand side of the tree over the right. Make sure you invest in Battlemaster and Vanguard as well. Horn of Valor is a must, even if you have to use all your points to get it -- who doesn't want party-wide Guard on a spammable ability?
Finally, you can use Casual difficulty and breeze through set-piece battles.