Harbinger (Collector)

Mass Effect 2
[[Image:HarbCollect.JPG|right|280px|[[Harbinger]] possessing a Collector. }}Presumably due to possessing the Collector General directly, harbinger can also control an individual Collector soldier in combat, and said soldier gains alot more strength, plus a few biotic abilities. The soldier(s) possessed by harbingers body starts to crack open showing magma like appearances on the skin.

Walkthrough
When fighting Harbinger, it is best to keep at a distance, since his ranged attack is slower than the average biotic/tech abilities. His shots are capable of stunning a character in one hit and can quickly bring down the average squad-mate in close quarters. He is also capable of possessing multiple Collectors in a single fight so it might be better to deal with the weaker minions first before focusing on the master (provided there is sufficient safe distance between Shepard and Harbinger-Collector).
 * In addition, when Harbinger possesses any Collector trooper in the fight, even if the host was near death (almost no health), this Harbinger-Collector would still become a full health unit, with fully-charged barrier and armor.
 * If you strafe left and right while in cover, almost all of Harbinger's attacks will miss you, including the slow shot that knocks you out of cover, even at point blank.
 * Although the Harbinger-Collector is a powerful foe by any right, during the short time it takes to transform/possess a Collector trooper, it typically floats above any cover, not moving or attacking. This presents a window of first-strike opportunity, giving you a chance in quickly ending a fight – a well coordinated Warp / Reave / Concussive Shot during its transformation/possession phase can sap away its barrier and even some of its armor. If your squad uses armor-piecing ammo, it will go down even faster. Once the Harbinger-Collector loses its armor, it will be dead, though Harbinger can possess another minion right after (if there still are surviving Collector troopers in the field), or join the fight with the next wave of Collector troopers.
 * If done correctly with inferno ammo, a soldier Shepard can strip its health away quickly using Revenant in close quarters