Scion

The Scion is a type of Husk which appears in Mass Effect 2. It is made from three Husks fused together and grafted around a single mass effect/biotic weapon on the left arm. The blue 'sacks' on their backs contain redundant organs and element zero sources to provide power for their weapons and shockwaves. Scions operate well alone or in pairs, hanging back as several Husks and occasional Abominations rush ahead. Less mobile, Scions provide fire support, lumbering behind the wave of attackers while firing weapons and discharging biotic attacks. Also, capturing Normandy's crew for the Collectors suggests that Scions can do much more complicated tasks than ordinary Husks, not simply kill the enemy on sight.

Capabilities
Offensive

The Scion is armed with Shockwave, but unlike the class power, the Scion's version is much more powerful and can deplete Shepard's shields with one hit, penetrate thin cover and knock back enemies. This powerful blast also travels a long distance. Scion also carries a weapons similar to an assault rifle grafted to its arm, but this weapon is only used at close range.

Defensive

The Scion is very heavily armored, but does not possess any barriers or shields. The armor also serves as its "health".

Tactics
The head of the Scion is located on its right 'shoulder' and is a confirmed weak spot.

In term of weapons, any player class that has a sniper rifle will have the advantage in a fight against a Scion. This allows you to keep the fight at a distance and have room to dodge its attacks. Paired with armor piecing ammo, this would be the best combo against it. If the sniper rifle is not available, the Collector Particle Beam is an efficient alternative.

There is also a second possible weak spot at the rear of the Scion in the form of a bright blue circle; however this requires a distraction to expose. Note: given the devastating nature of the Scion’s weapon and the size of the areas they appear in, it is dangerous to attempt such a tactic without absolute clarity on your approach.

In some of the fights (such as the platform ride before confronting the Human-Reaper), the Scions remain stationary and inactive if you keep your distance (the distance that doesn't trigger the HUD to display its health). In this scenario you can save a lot of pain by shooting it from far. Chances are you can eliminate the unit without it engaging you.

A tactic for Vanguards on Veteran and below involves using Heavy Charge to close on the Scion quickly, then blast away at it with an SMG armed with incendiary, all while backpedaling away. Works on hardcore if player has Geth Shield boost, which the player can activate if the Scion lowers their shields with its close-quarters attack.

Trivia
The Scion is named after the horticultural method of grafting plant tissues together.