Ravager

Ravagers are synthetic-organic creatures derived from rachni and mutated by the Reapers that appear in Mass Effect 3. They are mobile artillery pieces, with two limbs serving as long range weapon emplacements.

Capabilities
Offensive Ravagers are armed with two powerful long-range cannons. They will continually spawn small numbers of Swarmers to harrass their foes.

Defensive The large, fragile sacs on their bodies can be punctured (by gunfire or as reaction to melee enemies), releasing several Swarmers. These creatures, though individually fragile, are volatile in large groups, and can hinder shield regeneration in smaller teams.

Tactics

 * Bursting the largest sac on the front of the Ravager will reveal a green fleshy area underneath. Shooting this area will inflict high damage.
 * The glowing blue circle above the front sac is the Ravager's head and is vulnerable to head shots.
 * The Ravager's guns have a brisk rate of fire, high accuracy, and deal significant damage, traits that make them lethal over long range. However, they will rarely fire their weapons at close range, instead preferring to retreat to a safe distance (akin to the Nemesis).
 * If engaged at melee range, the Ravager will intentionally burst a sac of Swarmers, and this can quickly overrun your shields. When this happens, or if small-arms fire bursts a sac, use an area-of-effect power like Incinerate to destroy the Swarmers while damaging the Ravager.
 * Targeting lasers can be seen just before a Ravager fires its guns. Use this to your advantage by executing a combat roll or quickly getting into cover to avoid getting hit.
 * The Ravager's guns fire in salvos of three. Use the time window between them to return fire.
 * Using Stasis Bubble (Rank 6) on a Ravager will cause any Swarmers it spawns to be instantly killed during its duration.
 * A Ravager will leave behind a green puddle when it's killed. If you stand in it, even for just a moment, you will take damage over time for several seconds.
 * If the acid puddle afterdamage kills you in Multiplayer, other players will not receive a notification saying what took you down.
 * A Rank 6 Incinerate that has armor damage can take down a Ravager fairly quick on lower difficulty levels.
 * As counter-intuitive as it may seem, it's feasible to engage Ravagers with heavy melee attacks. This is especially true in multiplayer with krogan or batarian characters optimized for melee damage; one heavy blow from a krogan in a rage can take off about half a Ravager's health on Bronze. On higher difficulties, it makes for a good finishing blow.
 * In multiplayer, if you have Tech Armor or Barrier, it is a great strategy to run right up to a Ravager and shoot the sacs. Once all the sacs are broken, detonate the Tech Armor or Barrier to kill all the Swarmers. The Ravager will not shoot at you, but if it moves far enough that you begin to see its targeting lasers, run. Be careful, however, as this tactic is only really effective if the Ravager is alone and/or there are no enemies that can shoot you while you're up close with the Ravager.
 * A Ravager has a weak point akin to a head, right underneath the eye but above the front sac. An infiltrator with maximum damage options can kill a Ravager on gold in one hit with a well placed sniper shot from a powerful sniper rifle, like the Kishock Harpoon Gun.
 * Human characters can effectively dodge all three shots fired by rolling left and right quickly, if their timing is good.

Trivia

 * In initial concepts, a Ravagers' cannon was originally formed from a clearly discernible humanoid husk fused to the back of the rachni, this was removed when it was deemed to be too disgusting.