The Rachni continue to be a problem in Mass Effect 3 Legendary Edition. You initially encountered the last Rachni Queen in the first game, and you had the choice to free her or let her die. That decision matters the second time you meet the Rachni Queen after you discover she’s been captured by the Reapers and has forced her to breed an army for them. After you’ve saved Krogan’s only fertile female from the Salarians, the leader of the Krogan asks you to find their missing scouts that went after the Rachni.
This decision is during the mission Attican Traverse: Krogan Team. If Wrex survived the first game, he’s the leader. If Grunt survived the suicide mission in Mass Effect 2, he would be leading Aralakh Company. When you reach the end of the mission, you have a choice to save the queen or let her die.
Should you help the Rachni Queen escape or leave her?
The choice to let the Rachni Queen live or die is based on if you let her live or die in Mass Effect 1. If you let the Rachni Queen escape on Noveria, she will have remembered that you helped you, and when you let her escape, she becomes a war asset worth 100 points. However, even if you killed the Rachni Queen on Noveria, one will have been created by the Reapers, and you have the same choice, and you want to make sure to leave this queen.
The big difference between the two is the aftereffects. The Rachni Queen that you let live in Mass Effect remains an asset for you. The Rachni Queen that was created by the Reapers will initially become a war asset, also worth 100 points, but she eventually turns on you, harming part of your war assets. She destroys Aralakh Company and 100 points worth of your Alliance Engineering. The only time you want to let the Rachni Queen die is when you initially killed her in the first Mass Effect.
It’s important to note that regardless of what Rachni Queen is during this mission if you let her escape, Aralakh Company will remain behind to help her leave, dying in the process. If you leave her, Aralakh Company will live, becoming a war asset, worth 25 points. However, regardless of the decision, if Grunt is on the mission, he will survive unless you did not complete his loyalty mission from Mass Effect 2. He becomes a war asset at the end of the mission, worth 25 points.
Overall, it’s a better choice to help the Rachni Queen escape the reaper nest, but only if you let the one on Noveria leave. If you did not, leave her and get out of the caves with Aralakh company.