The M-76 Revenant unleashes a storm of high-velocity slugs. It has low accuracy but a high thermal clip capacity, and packs considerable firepower. This custom-made machine gun features technology not widely available. Protected against replication by sophisticated Fabrication Rights Management (FRM) technology, only the richest and most powerful warlords can afford the Revenant.
The Revenant also has a faster rate of fire than most other assault rifles, and does more damage per round than most full-auto assault rifles (in fact the only full-auto assault rifles that beat it are the Cerberus Harrier and Striker Assault Rifle, although the latter is a bit of a special case). This makes it very capable of shredding enemies at close to medium range.
To fully maximize the Revenant's damage potential, equip the Piercing and Extended Barrel mods. With both mods maxed the Revenant will shred through targets like paper mache.
The Revenant is one of the most powerful fully-automatic weapons in the assault rifle category (along with Cerberus Harrier which is much more accurate but has a much smaller clip, and the N7 Typhoon which has better accuracy and larger clip but is extremely heavy and has a spin-up time). Its high capacity, good bullet damage, and fast rate of fire makes this weapon brutally effective at close range, where accuracy is not an issue. On any difficulty its very lethal, but at ranges it suffers from lack of accuracy. A stability mod would definitely help here, or a stability upgrade (equipment).
It should also be noted that unlike other weapons, the Revenant actually slows you down when you fire on the move, although krogan and batarians are unaffected by this. One should utilise the Revenant in cover ideally or you could very easily end up filled with more slugs than you are dishing out.
The Revenant can become even nastier with the aid of a Piercing mod. The high capacity and rate of fire are very likeable, and damage isn't too badly affected when using the Piercing mod. This allows a weapon that can combat any enemy, even Guardians. It also allows more damage to be inflicted on enemies with armour, particularly Atlases, Brutes, and Ravagers.
The only class that can give it complete stability is the Turian solider with marksman with a rank 5 stability upgrade and the Turian Veteran. With the accuracy bonus of marksman it greatly helps in using it.
When fully upgraded the Revenant has 480 rounds on reserve, making it very capable of holding its own in long-term firefights. This may tempt you to use just the Revenant since it is quite versatile with its rate of fire, damage, and large magazine. The only real weakness is you may be inaccurate at longer ranges, though burst firing can compensate for this. It could even be used on its own with power-oriented classes like the Adept, or Engineer and still maintain a fair amount of power recharge speed.
The N7 Destroyer's Devastator Mode improves weapon accuracy (especially with the rank 4 accuracy bonus) which greatly reduces the primary flaw of the Revanant.