|The Sage in the Lighthouse|
Did You Not Get the Memo? - Defeat Mohmils waves in under 150 seconds. (Must side with Mohmils in Extermination) - 1000 Plex.
Backstabbing Rats - Defeat 5 Mohmils after they have been ordered to retreat. (Must side with Mohmils in Extermination) - 1250 Plex.
No More Nyrceffs - Defeat Nyrceffs in under 45 seconds. (Must side with CIR in Extermination) - 1500 Plex.
If you sided with the CIR in the last mission, this is easy. Your only opposition will be the three Nyrceffs. You'll need to actually land a hit on one to get it to stop moving to the other side of the map and attack you. Simply letting them go will result in mission failure when they reach the lighthouse.
Things are much harder if you sided with the Mohmils. You'll need to hold out against waves of Mohmils in rank 4 ships until they give the retreat signal. After they get the signal, they'll stop attacking you and start moving to the right side of the map. To get Backstabbing Rats, kill them while they're leaving.