Asari Valkyrie Sentinel

Asari are the most influential and respected sentient species in the galaxy. They are native to the planet Thessia and were the first species to discover the Citadel. Their long lifespan and history have allowed them to serve as galactic mediators for centuries. While not as physically powerful as other species, their proficiency with biotics makes them dangerous opponents.

Asari are fierce, graceful warriors. They are incredibly powerful natural biotics. The asari excel at hit-and-run tactics to ruthlessly eliminate their opponents from the battlefield.

General Notes

 * The Valkyrie works very well as a Biotic Explosion primer. With Tech Armor and Annihilation Field maxed out, one can run close to enemies with relative impunity, thus allowing teammates with low-recharge biotic detonators to have a field day.
 * With a properly specced Volus ally, the Valkyrie can achieve up to 90% damage reduction, allowing them to serve well as a front-line shock troop.
 * When the Rank 5 Damage Taken evolution is taken, Annihilation Field can allow the Valkyrie to serve as a mobile and highly defensible living debuff. Roam into the midst of some foes, and watch your teammates destroy them all with AOE attacks.
 * When the Rank 6 Drain Evolution is taken, Annihilation field can fuel your Warp with vampiric properties, making this already durable class even harder to kill. One should however be cautious on harder difficulties, as even this will not stop you from being shot down by large clusters of enemies, or squads of deadlier foes like Phantoms, or Primes. Alternatively, a weapon with an innate damage bonus against shields or barriers such as the Reegar Carbine or Acolyte used at close range will allow you to refill your shields extremely quickly while devastating foes at the same time.
 * Because the Valkyrie is a biotic specialist, a lighter loadout will give better cooldown timers, while a slightly heavier loadout will allow a Valkyrie to tackle more problems on her own. A lighter sniper rifle will give a long range edge where powers may not reach while retaining a good level of damage, while an assault rifle will give you an all round weapon. Shotguns and SMGs synergize well with the Valkyrie's close-range nature.
 * If one decides to forego Warp and detonations of the Valkyrie's other powers, a heavy weapons build is viable for the Valkyrie. Specced for maximum durability, she becomes capable of taking and inflicting massive amounts of damage at close range while setting up Biotic Explosions for allies to detonate.

Cerberus

 * The Acolyte will work wonders at ranges outside your reach and affect groups of foes and deal with shields/barriers very effectively.
 * Annihilation Field CAN hit through a Guardians shields, but at the range you need to do this, it would probably be better to bring a piercing mod or piercing weapon to deal with such foes unless you are behind cover while hitting them with said power.

Collectors

 * The Rank 6 Drain evolution of Annihilation Field is recommended, as many enemies have barriers.
 * It is highly recommended to keep your Tech Armor on, as the enemies specialise for ranged attacks, and the Praetorians are very lethal up close too. The Tech Armor can give you the protection you may well need to escape if said foes close in on you or protect you significantly from enemies who focusing their fire on you.
 * Warp will prove very useful as well since all enemies are vulnerable to Warp in one way or another. Standard troopers can be easily killed with one or two Warps, protected enemies will have their barriers stripped, and armored enemies will be softened for your biotics, or you and your teams weaponry.
 * If you are trying to deal with a Praetorians protective barrier, it may be best just to blast it with the Acolyte if you have it equipped.
 * Annihilation Field is useful for dealing with Seeker Swarms, either with its own damage over time or for allowing Biotic Explosions to be easily and repeatedly triggered.
 * Be wary of Abominations and Praetorians if you get in close; Abominations' explosions can do a lot of damage even when specced for maximum durability and Praetorians can quickly assail and overwhelm you.

Geth

 * The Rank 6 Drain evolution of Annihilation Field is recommended, as most enemies have shields. In fact it is highly recommended to keep this power on at all times, as the Geth are notorious for stunning you and your squad, and this power may just give you the edge you need to survive.
 * Warp will prove effective against the Pyros, Bombers, and Primes.
 * While a close-range build is less risky against the geth due to their lack of melee instant-kills and abundance of shields to drain, Pyros still pose a considerable threat.

Reapers

 * Annihilation Field does a fantastic job of killing swarmers. The Tech Armor will also work for this situation, but it is ill-advised since it protects you from 35-50% damage taken.
 * Warp will allow you to detonate combos on the enemies that draw close, but will prove fatal if you try it on with the Banshees.