Geth Juggernauts are recognizable by their red armor, bright red "flashlight eyes" and huge stature. Like the Geth Prime, they tower above the ground, an intimidating presence on the battlefield. They're equipped with pulse rifles modified to fire Distortion Rockets, similar to weaker Geth Rocket Troopers.
Juggernauts possess four to six bars of shielding; as is the case with all Mass Effect enemies, it will regenerate over time. Their health is considerably higher than usual, but it doesn't regenerate, similar to other synthetic enemies, unless aided by a Repair Drone. They don't move around much and rarely use cover.
Their Distortion Rockets don't travel very fast and can be dodged rather easily at medium and long range. They do a lot of damage, however, and can easily kill weakened or low-level Shepard with a single shot.
Due to their lack of secondary weapons, Sabotage will leave them completely defenceless until their weapons cool off. Overload and Warp are both good abilities to lower their defenses and make them more vulnerable. Keep in mind that due to their size, low-level Pull, Throw and Singularity wouldn't affect them.
If accompanied by a Geth Repair Drone, destroy the drone first to prevent it from regenerating the Juggernaut's health.
On Feros, they're often encountered in small groups, supported by Geth Armatures. Under these circumstances, killing them outside of the Mako is very difficult, but will yield you more experience.
Being synthetic, Juggernauts can be turned over to your side using Master-level AI Hacking. They make for excellent allies due to their powerful weapons and defences. Beware that if there are no geth in its line-of-sight, it will continue to attack you.
They're the first enemy unit in the game to possess both shield and armour, and as such can be considered the game's first boss-type adversary. Like with other enemies, their shielding will regenerate over time.
Like other enemies in the game, Juggernauts are vulnerable to headshots. Due to their size, it is particularly easy to do that.
Since they're equipped with shotguns, they're only dangerous at short range and their slow movement speed leaves you plenty of time to shoot them. Regular Geth Troopers should thus be targeted first due to the greater range of their weapons.
Most of the time, Geth Juggernauts are dropped by a geth dropship and can then quickly arrive in range for their shotgun.