ME2: Thresher Maw defeated

ME2: Gain the loyalty of Archangel

ME2: Complete a mission discovered by scanning an unexplored world

ME2: Help the Justicar resolve her mission

ME2: Complete the investigation of a derelict alien vessel

Kill The Black Hand.

Kill The Tower.

Kill the Great White Graug.

Complete all Acharn Legend Missions.

Help a Captain survive a Recruitment Power Struggle, and then kill him and all his new recruits.

Complete all Outcast Rescue Missions.

Kill all 5 Warchiefs before any uruk take their place.