Antlion Guardians appear physically identical to Antlion Guards, but have a different coloration and are capable of bioluminescence.
Apparently, each Antlion hive has one Guardian that lurks near the larval clusters. The Guardian patrols the "Nectarium" (center of the nest), keeping watch for nest raiders. Guardians are extremely protective of Antlion Grubs, the extract of which is used by Vortigaunts to manipulate the Vortessence, and will ferociously attack intruders in order to protect them.
Should someone enter the "Nectarium" for larval extract, the Guardian will attack and may pursue the thieves for some distance (in Episode Two, a Guardian follows Gordon Freeman (whose Vortigaunt companion had taken the extract) outside and battles him).
It is notable that the Guardian is very similar to the Guard, both in name and appearance, but there are numerous differences: the Guardian often lives deeper within the nests, protecting and ruling over the Antlions and eggs within. Comparatively, the Guard will work closer to the surface, protecting nest entrances, and offering backup for workers. Also notable is the Guardian's natural bioluminescence, which is presumably caused by it living in deeper darkness. The Guard also has a very different coloration, consisting of more varied and contrasting colors.
Behavior and skillsEdit
Guardians have basically the same capabilities as an Antlion Guard, but with the added effect of a deadly neurotoxin somewhat like that of the Poison Headcrab. However, when fought on the surface in the chapter Freeman Pontifex, the Guardian doesn't have its neurotoxin effect. This may be due to sunlight affecting it.
When fighting the Guardian, be sure to keep a good distance away from it. Its headbutt attack is quite powerful, and can send the player flying quite a distance — or result in instant death if they should happen to be pinned against a wall. These attacks also have a poisonous side effect, which reduces the player's health, regardless of the current amount, to 12 — but the Guardian, unlike the Poison Headcrab, can actually kill the player if additional damage is caused.
When the Guardian chases the player through the hive tunnels, one should not attempt to fight it as it is invincible. The narrow tunnels don't offer much room to dodge around the Guard and avoid its charge, so it is advisable to take cover in the 'grub tunnels' instead.
Be aware that the guard is able to move much faster than the player, even while sprinting. If necessary, the player can try to use the MP7's grenade launcher to stun the creature for a few seconds if it is hit it in the midsection.