The Advanced Ceph Assault Units, or otherwise known as "Guardians" are the most powerful of on-foot Ceph units in Crysis 2. They appear to be the original Ceph -- much like the ones at Tunguska -- as they possess the ability to cloak, which is not present in other Ceph warriors.
Guardian Units drop 5,000 Nano Catalyst upon death (Crysis 2 only).
Guardian Units wear silvery-metallic armor that appears to be a cross between that of a Ceph Stalker and a Ceph Grunt but they also wear special helmets like the ones used by the Ceph Commander. The helmet's visor changes color depending on the situation - - white when passive, red when fighting. Like Ceph Stalkers, a Guardian Unit's tentacles protrude from their exposed area. However, their tentacles are colored black instead of pink or red.
In combat, Guardian Units act like extremely powerful versions of the Ceph Stalker; they share both fighting tactics and overall design. But their health is on par with the Ceph Devastator, though incapable of surviving a direct hit from the JAW on Soldier difficulty.
Due to their dangerous stealth ability and high health, the most effective weapons against Guardian Units are the Grendel (if used correctly), the HMG, C4, JAW, DSG-1, X-43 MIKE, and the M2014 Gauss. The K-Volt can paralyze them, and is found on their part of Central Park, allowing the player to easily melee them or get a few headshots. Cloak Tracker will also reveal their position.
The K-Volt is the easiest to use against them, since one can be picked up before encountering them. The player only has to hit them with a few rounds and melee them until they are down and the player gets their Nano-Catalyst. If one cloaks, the player can simply hit it again. The player only has to be careful not to get swarmed by all of them. It is best to just camp at the entrance, wait for them to come and kill them one by one. This works good on the highest difficulty (Post-Human Warrior).
Since they are dangerous even on Easy difficulty, stealth kills and grabs are very useful. The best thing to do is to enter Stealth Mode just before you face them and then mark them with the visor. However, it may be they can see through your cloak better than average grunts.
Another tactic is simply taking them out one by one with stealth kills. If they see you, just hide and wait until they stop looking for you. Repeat this process until all of them are dead. Never engage them head-on all at once. All four of them attacking you at once will kill you almost instantly. Take them down one at a time.
One of the most astonishing techniques that can even take down multiple Guardians in a single hit is utilizing the Taxi. There's a Taxi in the corresponding arena that can be power-kicked. The player may lure them to the path by utilizing the Cloak mode. Hitting Guardians with a power-kicked Taxi instantly annihilates them. The tunnel that you go through cannot be traversed back again, but can be hid in.
Appearance in Crysis 2
Even though the Ceph Guardian Units serve as the "endgame boss", they appear several times before they're actually fought, as early as "Gate Keepers"; a single Guardian Unit investigates the tomb at the end of the level. The Unit notices Alcatraz and flees. Another one appears the mission "Seat of Power" where two are seen, one walking on a destroyed bridge, the other standing on a flaming bus, but both only flee as well. In "Train to Catch" several Guardian Units can be seen when Alcatraz enters the library right before he has to walk through the fire, these too cloak and run away again.
The Guardian Units are finally seen and fought in "A Walk in the Park" where four of them serve as the boss encounter of the level. Alcatraz must kill all of them to gain access to the Central Spore Regulator.
In Train to Catch, the player can sometimes get the Guardians to hold still and uncloaked by freezing as soon as they are seen. They will still be invincible, however.
- While the exposed jelly of Guardian Units is colored black, they bleed pink, which is most notable via stealth-kill.
- Guardian Units are the only enemies in Crysis 2's singleplayer who can cloak.
- The Guardian Units on The Gate Keepers can be temporarily imobilized by the K-Volt and if done quickly enough or stealth-kill them. The Guardian Units in the mission Seat of Power can drop catalyst for an easy 10000 catalyst early in the game.[][].
- In Crysis: Legion, near the end of the novel, Alcatraz encounters a Grunt-type Guardian Unit before fighting against the Stalker-type Guardian Units.