AoTN takes place after beaming from the Defiant onto Terok Nor. During this time, the mission actually takes place during the time frame that the space Mission: Counterpoint occurs. So while you are on Terok Nor, your ride is actually out and about, assisting other captains in the defense of Deep Space Nine.
After Beaming on board Terok Nor from the Defiant, you and your assault force will make your way through the hallways of the alter-world version of Deep Space Nine. There are multiple stages involved within this assault, defend the hackers, align the consoles, and rescue the orb from leeta.
First Wave[ | ]
The first phase, after making your way through the hallways, bring you and your group to a two fold bottleneck of choke points which contain several consoles, and you must defend your hackers against the Terrans who are transportering in every few seconds. This phase runs off a timer, and once successful, you will move on to the second phase.
Second Wave[ | ]
After leaving the choke point, you find a forcefield in the hallway, blocking your advance. Here, you meet Admiral Leeta, who speaks at great length from the promenade. This is technically a fight of attrition on both sides. Not only will you fight ground forces, but on the upper levels of the promenade, you have Tactical officers lobbing explosives down on you. Four people will kill the defenders, while the 5th must activate consoles. There are six consoles here, located at various points in the room, five of them must be activated within the right order, failure to find the right order will reset the consoles.
Third Wave[ | ]
Phase three: the next doorway leads you to the final fight with Leeta and her Terran cohorts. There are three consoles in this chamber, and three electro pads. When Leeta is on one of the pads and the corresponding console is activated, she will be zapped and her shields offline momentarily. Up until this time she is quite invulnerable. While her shields are offline she may be blasted, prodded, smacked, scratched, zapped, shot, exploded, set on fire, frozen, grenaded, mortared or other means of wanton violence, but it does not last. It will take several console pads to wear her down. When she is low enough, she will give a magnificent speech and transporter away, leaving the orb free to take back to the Prime Universe when the assault squad transport back to the Defiant. It is at this time that both Assault on Terok Nor, and Counterpoint matches effectively end.