Mission: Broken Circle/Walkthrough

Shipyard
To start the mission, go to the Kyana System in the Delta Quadrant. When you beam in, speak to Tullek and head to the room on the right. After the cutscene, speak to Researcher Jelen and then head to the conference room. Speak to Kagran, and then Phillip Crey. After that, begin the briefing. Once the briefing is over, beam up to your ship.

The Direct Approach
Dealing with Heralds in space can be tricky, and if you want to have almost constant uptime of abilities, you will need to have Engineering Team and Science Team to clear debuffs. Engineering Team clears the Herald EMP Probe and the Iconian Viral Probe, whereas Science Team clears Subnucleonic Carrier Wave. It is recommended you don't use Evasive Maneuvers on the third sector so it's off cooldown for saving the ships. For this, it's recommended to go Federation > Klingon > Romulan, in order to save all 3.* Once they are dealt with, an Iaidon Dreadnought will appear, but not be able to be fought. After the cutscene plays, go through the gateway.

(* If you can turn quickly enough at full impulse, you may use that instead of Evasive Maneuvers; repair each ship while turning around it to remain in range, starting with the ship with the least time, and ignoring allegiance.)

Boarding Action
In this segment, you will mostly be fighting Baltim Raiders, and Vonph Battleships, with the odd Quas Cruiser mixed in. It's recommended you have Science Team and Engineering Team equipped to combat their disable abilities. After the first wave of Baltim Raiders have been dealt with, three Carriers (An Armitage, Ar'kif, and Negh'var) will appear, you need to keep the Herald Forced off of their backs so they can release shuttles to the Iconian Flagship. Once 18 shuttles have boarded the ship, the rest of the Herald Forces will disappear, and you can beam to the flagship.

Deicide
For most of the mission, you will be fighting Constructs and Thralls. Towards the end, there will be a Harbinger and a few Defilers. Once the heralds who are fighting Tullek and his boarding party are down, speak to him. Then proceed to save the Romulans and Federation Officers on board the ship. Once this is done, go to the first power junction. This will summon M'Tara. The easiest way to end her boss fight is to use the Tier 5 Delta Alliance Reputation Power, as this disables her shields, which is needed to proceed the fight. M'Tara herself has the standard abilities as a Herald Harbinger. For her fight, a TR-116B should not be used as it doesn't damage shields. The boss fight follows the same pattern until the end room, where there are 4 power junctions instead of 2. Activating the last one will end the boss fight, and play a cutscene.

Aftermath
This segment contains no combat, and is just flying towards the two markers on the map where you need to scan objects.

Debriefing
The game will return you to Kyana, where you need to talk to Kagran, Nog, and Tom Paris. After this, the mission will end.