Infiltrator Guide (Mass Effect 3)

While focusing on taking out enemies from afar without detection, the Infiltrator also specializes in flanking and misdirection, serving to disorient the opponent.

Overview
The Infiltrator uses its powers to create opening which can be exploited by other powers or weapons. Tactical cloak lets an infiltrator maneuver into position AND set up attacks without enemy targeting. Sabotage temporarily disables enemies OR turns them against their allies (through the AI Hacking feature). Incinerate provides some help against armor, Sticky Grenade can be quite useful if your aim and timing are good, and two ammo powers help give the Infiltrator some variety.

Tactical Cloak
As in Mass Effect 2, the Tactical Cloak is one of an Infiltrator's greatest assets. Not only are you able to move around enemy lines undetected, but the next shot you take gets a considerable damage bonus. New to Mass Effect 3 however, is that disabling the Cloak before it wears off will reduce the cooldown of your powers, allowing the cloak to be turned on and off more frequently. In addition, the weight system allows infiltrators to take a shotgun into combat in lieu of or in addition to a sniper rifle, granting the same damage bonus from the cloak, but at much closer range. This allows an infiltrator to maneuver around enemy cover and deal damage in situations where a sniper rifle has a high chance of missing or being blocked by armor (which is particularly helpful against Cerberus Guardians).

Cryo Ammo
Cryo ammo best used with weapons like Assault Rifles and SMGs--weapons that spray many shots, further increasing the chance of icing an enemy over. If you're quick at changing weapons and aiming, a sniper rifle shot can finish an enemy off--or you could use Incinerate. Cryo Ammo also softens up armored enemies, making it a good thing for wearing down Brutes, Banshees, Atlas Mechs, and anything else with armor as a protection. This ammo is particularly devastating when used with the Falcon, as any enemies caught in the area of effect are all susceptible to being frozen. Another tip is to evolve the squad version and allow your squad to stop entire squads of enemies. This also enables the player to use a different ammo type while still taking advantage of the freezing debuff on enemies (e.g. frozen Brutes + Armor-Piercing Ammo).

Disruptor Ammo
Disruptor ammo is eternally useful. It fries shields and synthetics, while also having a decent chance to stun organic enemies. It's not a bad idea to get the Squad Disruptor Ammo evolution, but it's hardly essential.

Sticky Grenade
Sticky grenade is useful mostly because it is has no cooldown and can be used at any time. It fairs well against single, well-armored enemies, as they are often large targets which require much less effort to stick than the standard grunt. When stuck, the grenade deals massive damage, but unfortunately its damage radius is quite small, meaning a miss is unlikely to deal much, if any damage to moving targets. Guardians will not take any damage if you stick the grenade on their shield.

Incinerate
Incinerate's relatively quick recharge, solid damage, and anti-armor abilities are good features to have along. One of its late power evolutions does greatly increased damage to frozen enemies, making it self-synergize with Cryo Ammo above. Remember that the shot will curve towards the target, so it can be used to break enemies out of cover. On high-level difficulties, evolving Incinerate towards its anti-armor role makes dealing with Brutes, Banshees and Harvesters much easier.

Weapons and Equipment
In Mass Effect 3 there are several highly effective load-outs possible due to the variety in Sniper rifles, your primary weapon. The typical load-out for an Infiltrator would be a Sniper rifle and a Heavy pistol or Submachine gun to give space for a high enough power recharge rate. Though never essential, the Infiltrator can switch out for an Assault rifle or Shotgun.

The M-13 Raptor is most effective for lightweight players, the low damage is offset by the high rate of fire and high-capacity clips and can be enhanced with Armour-piercing Ammo and Sniper Rifle Extended Barrel for maximum stopping power.

Another notable weapon for an Infiltrator is the M-97 Viper, coupled with an M-6 Carnifex or M-77 Paladin as a sidearm. The Viper's advantage over other Sniper rifles is its thermal clip size of 6 and its pretty high reserve, its fairly low weight, its extremely fast reload speed, and its low recoil coupled with a decent fire rate. The damage it delivers may not kill most targets in one shot, but it can leave most opponents at a very low health with a single headshot, allowing you to finish them off with your devastating sidearm. Another great thing about the Viper is its low weight, making power spam a viable tactic. If ever one is against multiple opponents with armor or shield, one can throw Incinerate or Energy Drain (provided you have it as a bonus power) at a fairly fast rate. It's main weakness is the need to score a headshot to actually deal any recognizable damage, and its lack of penetration through surfaces.

You can also choose for a Soldier-type approach by carrying a Sniper rifle, Assault rifle or Shotgun and a Heavy pistol or Submachine gun, at the cost of power recharging speed. For flexibility's sake it is advised that when you actually do choose an Assault rifle like an M-8 Avenger or a Shotgun like a Disciple for a sidearm, a single-shot or low-capacity Sniper rifle like the Javelin should be coupled with it.

Furthermore, a high-risk, high-reward tactic is to choose for a hard-hitting Sniper rifle, like the Mantis or Black Widow, and pair it together with either the M-300 Claymore or the M-11 Wraith for a massively damaging load-out allowing you to take out the toughest enemies with minimal effort from any range. Choose squadmembers that carry Assault rifles and have ample biotic or tech powers, coordinate them well during fights and you'll be a near-unstoppable force.

Another build of an Infiltrator completely removes the Sniper rifle as the primary weapon and change its role to more of a support weapon (or remove it entirely if one desires). The build revolves around melee damage and close range combat using Tactical Cloak, which means that weapons should revolve around the Shotgun or Heavy pistol family with the appropriate melee damage increase mod. It is suggested to use a Shotgun though since one point-blank shot can decimate the opponent's Shield, making it easier to melee enemies to death.

Combat Guide
Much like Mass Effect 2, infiltrators can take full advantage of a good sniper rifle like the Mantis or Widow. Use Tactical Cloak, flank, and take a shot. To get the sniper-slowdown effect, put a concentration mod on the rifle--it will also increase the damage slightly.

Incinerate is useful for finishing weak enemies, hurting armored enemies, and flushing targets from cover (remember that it arcs to the target. Aim a little high and to one side of your target to help it around cover). While it's not on the level of Tactical Cloak, it's nonetheless a valuable part of your arsenal.

Sabotage doesn't do much damage by itself, but it can remove a strong enemy from the fight long enough to attend to the weaker enemies, or end a weakened enemy (from the backfiring of his weapon) while you move onto the next one. It's also very useful for shutting down Atlas mechs to give you a few retaliation-free shots at it. The AI Hacking function is extremely handy to have; Cerberus turrets are very, very effective, and often set up in the middle of an enemy position. It's not an exaggeration to say that one subverted turret will ruin any troopers, engineers, or Centurions that happen to be near it. AI Hacking still has the same uses against geth that it always had--subvert a target in the back of the group, and he'll either divert attention to himself or flush enemies from cover, or get killed himself while softening up the group as a whole.

Sticky grenade is good for slow-moving or large targets, like Brutes or Banshees. If you can get close enough, try throwing a grenade on them. Few things in the game do damage like a grenade that just went off on an enemy's shoulder. The sticky grenade is also good for tight groups of enemies.

Disruptor ammo helps remove shields and destroy synthetics, and sometimes stuns organic enemies. Cryo ammo is good for its armor-softening abilities, even if it doesn't freeze the target.

Squad Members
If you're playing as a sniper, Liara is invaluable. Stasis locks enemies into place and allows you to get a headshot lined up; it also works on shielded enemies, allowing you to eliminate Centurions, Engineers, Marauders, and other mid-level enemy types right there. Enemies caught in a Singularity are not hard to hit with through a sniper scope, either. Warp and Warp Ammo help strip barrier defenses (and Warp Ammo is not a bad idea to have along as a bonus power on many missions). And, finally, her Singularity can strip the shields of those pesky Guardians--and its recharge time can be made quite short, allowing her to use Warp on enemies within it before it expires for extra damage.

Characters who have Overload, such as Garrus, Kaidan Alenko and EDI, are also good to have along. In addition to removing shields so you can take out one enemy with a sniper round, Overload often stuns organic enemies for a few seconds, giving you the opening for that sniper round. Cryo Blast, also possessed by Kaidan, will also freeze unprotected enemies, allowing a sniper to quickly destroy and shatter them.

For other guidelines, characters who can use assault rifles (Ashley Williams, Garrus, Javik James Vega, and Kaidan) are good to have, especially with the piercing mod to help get to the enemies behind cover. From Ashes also adds the Prothean Particle Rifle, which is an amazing tool for focus-fire.

If you have the DLC From Ashes, Javik is also a very reliable option and can even effectively replace Liara's position. Javik's powers are somewhat similar to Liara's if evolved around the appropriate steps; by giving his Pull and Slam the ability to affect multiple targets. Javik also has a very low recharge speed towards both said powers, allowing you to spam them effectively.