The Descent is the final step of character creation in Agora. It's like a little mini-scene, and is totally stolen from DitV. Here's a full, top-to-bottom example of a Descent that I just wrote and am rather fond of. This is how you start a game of Agora:
Judson’s Descent, Start to Finish
Now it’s Judson’s turn to play his Descent incident. To his left sits Colin, who will be running the obstacle. Judson decides to play his character, Admiral Wargrave, through the Battle Above Agora.
He sets the stage: “Wargrave’s battle group, a handful of destroyers clustered around the command carrier Kingsrook, is laying waste to the ranks of Diamond and Uprising warships over the north pole of Agora. The battlegroup operates with pure military precision, with each part doing its job and every soldier putting Wargrave’s commands into effect. We have the last Alliance carrier in our sights when the transmission about the Peace comes in.”
Judson also rolls in his ideals and resources. First his 3d8 Legionnaire ideal, which rolls 2, 4, and 6, then his 2d10 Hierarchy ideal, ending up with 3, two 6s, 7, and an 8. By rolling in so many ideals, he’s making sure he’ll get to write the incident’s opportunity. He then rolls in the Kingsrook itself at 5d6, rolling a 1 as well as 3, two 4s, and a 6. He could narrate a bit more to represent these two ideals and one resource, but he’s pretty much covered all that with his opening narration.
He has, however, rolled a 1, which he must place immediately. Since he does have the largest ideals pool (his five versus Colin’s zero), he can define the opportunity now. He writes his goal, “Maintain command over Hierarchy forces post-landfall.”