(The Darkspawn DLC is pretty fun, I recommend it!)
Here's my resume for the writing team:
Instead of being a Kill Bill-style mission, you assemble a strike team to go back into the Fade and pull out whoever you left behind. Since you could have left someone from DAO or someone from DA2 in there, your strike team is comprised of companions from both games. Dorian is the character who suggests it - he's been going through Alexius' old notes, and he thinks he's figured out a way to manipulate time so you can show up right before whoever you left dies.
You play as Varric - either to go save Hawke, or at the request of Hawke, who can't abide the thought of a Warden dying to save them.
Your companion options are:
- Bethany/Carver
- Anders/Fenris
- Alistair/Loghain
- Recruit Blackwall
- Nathaniel Howe
- Oghren
- Zevran (he's doing this as a favor to Alistair/the Hero of Fereldan/Morrigan)
- Dog
Objective #1: You first have to figure out a way to get into the Fade in a "let's not destroy the world" kind of way, and Varric takes you to Merrill, who, with Morrigan, helps you get into the Fade.
Then you have to fight through various levels of the Fade. You come to a Pride demon who aaaaalmost kills you, before the spirit of Wynne shows up, saves your bacon (like she did so many times in Origins), and tells you the secret to defeating the Nightmare Demon.
The DLC ends with you pulling Hawke/the Warden out of the Fade and into the chaos of Weisshaupt Fortress.