The volus homeworld, Irune, has a high-pressure atmosphere that supports an ammonia-based biochemistry. To survive on other planets, the volus must wear pressure suits and breathers or, when facing combat, specially sealed armor.
Volus are cagey support specialists that use the most technologically advanced power armor credits can buy. Not to be underestimated, the diminutive volus adept more than makes up for its size with biotic abilities that are nothing short of godly.
Defensive Stance - The Volus Adept cloaks to avoid enemies, or while stationary generates a protective shield sphere that damages nearby enemies.
Combat Roll - The Volus Adept rolls to quickly evade incoming attacks.
It's advisable for Volus characters to put all fitness upgrades into shields and health, as the volus heavy melee is the only means of dealing melee damage; This form of damage is relatively weak even with bonuses.
The Volus Adept's light melee attack, rather than dealing damage, will instead activate a short-period cloak that lasts 3-4 seconds. Its heavy melee attack will generate a shield surrounding its body, which will temporarily increase your damage reduction and slowly regenerate your shield.
Since the volus' height is around half the height of a regular human character, they cannot take cover normally, but can take "soft cover" by simply walking into it.
Without Shield Boost, Volus classes are extremely brittle. Their health will only be 240 at best, even less than Geth without fitness, and their barrier is only 825 when fully upgraded.
The shield boost power makes them a medic on par (or even better) with Geth Engineer's Turret, while Geth turret recharge one ally's shield at long range, Shield Boost recharge all allies' shield around the player. Properly specced, this ability can restore ~1100 shields, plus ~220 per second for 3 seconds. The final slot of this ability further increases damage reduction, giving all affected players 50% damage reduction for 6 seconds. Combined with a cooldown approaching 2 seconds (4 biotic orbs, light weapon), this makes Volus adept an ideal support character on gold difficulty. What it will not do however is mitigate the "shield gate" aspect of damage - and this can prove fatal if a hard hitter strikes you, such as Atlases, or Phantoms, especially if you are physically frail.
The Volus's Biotic Orb power inflicts weak damage but grants a large bonus to power recharge rates while active- +10% per orb (15% if upgraded properly). If it is further evolved with increased recharge rate and extra orb abilities, it provides a total of +60% to power recharge abilities. Combined with a very lightweight gun like a pistol or SMG and the Volus Adept can perform Stasis and Shield Boost almost continuously, allowing it to greatly support allies.
Stasis can be detonated with Biotic Orb, combined with a low cool-down and right power evolutions, a Volus is able to create 4 Biotic Explosions in very quick successions.
Weapons that stagger enemies e.g. Falcon can be a good tool for Volus' survivability.
The Rank 6 Expose evolution of Biotic Orbs can help to inflict a great deal more damage on one's foes, especially if the Rank 4 Impact Radius evolution is also taken. Being able to allow your whole party to inflict up to +45% extra damage on a number of different foes can make a huge difference, especially on higher difficulties. If, however, you aren't likely to use Biotic Orbs as an attack, simply select Rank 6 evolution Orb Count instead. Being able to spam Shield Boost more quickly makes a large difference as well.
Instead of going for weapon damage at rank 6, one can opt for weight reduction. If one should do this, then the Volus class can take the Acolyte without penalty, and they can even take certain assault rifles for 200% Cooldown, or M-13 Raptor or M-97 Viper with them and still have 195% Cooldown rate. This results in a class that is very capable of anti-shield/barrier work, and can excel long range combat without compromising on the cooldown of the Volus's Shield Boost and Biotic Orbs skills.
Interestingly Shield Boost also gives a second or two of brief invulnerability upon activation. This can prevent a fatal attack from killing you if you haven't been given time to recover naturally. It will also bestow this trait onto your allies, increasing Shield Boost's tactical value even further.
Biotic Orbs can compensate for a heavier loadout—especially useful as Biotic Orbs is the Volus Adept's only offensive power. A potent combination is to use a chargeable weapon such as the Kishock Harpoon Gun, Arc Pistol, or Geth Plasma Shotgun—Stasis can be used to immobilize a target, setting them up for a charged shot. The Volus's "melee" cloak can make this strategy much less risky.
A Guardian will prove a significant threat since they can block your orbs should you use them. Stasis can sometimes be blocked as well, or you may need to target someone else with Stasis, so a piercing mod, high velocity barrel, or piercing weapon will work well here.
However, if evolved into Bubble, Stasis cannot be entirely blocked, meaning that the Guardians will resist it at first, but will proceed to walk right through it, only to be paralyzed and drop their shields.
Dragoons should be avoided at all costs, since they can very quickly strip you of all shields and health. Unfortunately Volus cannot take cover, so they cannot avoid the lashes by taking cover. Phantoms are even worse due to their deadly ranged attacks. One hit will destroy your shields, and the second, your health. Shield Gate will not help you survive a second or third hit so Shield Boost will be useless against Phantoms but can be put in stasis.
Stasis is going to be your mainstay power against Cerberus, since the only enemies that cannot be affected are the Combat Engineers turrets, the Atlas Mechs, and the Dragoons. Whole squads can be trapped in the bubble if evolved into a Stasis bubble, and can be hit hard by your Orbs, or by explosive ordinance.
You will really struggle against the Geth due to the lack of any real offensive powers. You can use stasis, but only to minimal effect due to the fact that armored enemies are immune to stasis. This limits its use to Hunters, Troopers, and Rocket Troopers.
You may be able to provide yourself some protection against the Geth by getting to cover that's taller than you are, but you may end up flanked and you wont be able to fight back. Considering Volus are more support races this tends not to matter.
You will need the Acolyte to be sufficient against the Geth due to the lack of any anti-shield power.
Your choice of weapons will be the main factor of your effectiveness against the Reapers, and is probably the only faction you can safely take on. Husks can easily be dispatched, Cannibals and Marauders can be put in stasis, and the Brutes, Ravagers, and Banshees can be taken down with the use of an anti-armor weapon.
For the barriers, your orbs fill that role if you use them carefully. But make sure you keep your shields topped up, or you may end up being the latest casualty on the field.
Avoid direct conflicts with the Collectors, as the majority can inflict serious damage, especially on harder difficulties, where enemies will be harder to kill and hit harder and faster.
Stasis once again serves little use against this foe, with only the Captains, Troopers, and Abominations being susceptible to it. Continue to serve a support role, and you should be fine.