Poison Zombie

Poison Zombie is the result of a human host under the control of a Poison Headcrab. The mutations that take place produce a bloated, slow-moving zombie that is capable of carrying additional Poison Headcrabs.

Appearance & Capabilities
Poison Zombies are bloated, reddish purple, slow-moving menaces. They are almost always seen carrying an additional 2 or 3 Poison Headcrabs on its back, it appears that the Poison Zombie's model is an old man's.

Poison Zombies have the same melee attack as all the other zombie variants, with the elongated claws on its hands. Poison Zombies are also the only zombie variant that has a ranged attack aside from gonomes, being able to throw the hitch-hiking Poison Headcrabs on its back at a target with great strength and accuracy.

Another trait that distinguishes Poison Zombies from other zombie types is its endurance. Poison Zombies can take 3 times more damage than other zombies before collapsing.

The Poison Headcrabs riding on the zombie's back can also leap off when needed to attack on their own.

Poison Zombies themselves are not poisonous, and rely on the hitch-hiking Poison Headcrabs to attack first. Then, it resorts to its claws. Poison Zombies can be detected by their loud, strangulated breathing and muffled groans. They also emit loud, whale-like sirens. Upon dying, some players have heard what sounds like a faint chuckle right before it dies. This could possibly mean the human host is just alive enough to be glad to die and cease suffering.

Poison zombies are unique in the fact that the headcrabs latched to their bodies appear to be interacting with their host. While other headcrab zombies serve as a host for individual headcrabs, the poison headcrabs attached to a poison zombie appear to be from it. The fact the poison zombie is off color and bloated would suggest that the headcrabs are either sucking nutrients from the body, are causing enough damage to make the host lose almost all of his blood, or are using the body to store or create their acute neurotoxin. It has also been speculated that poison headcrabs may lay their eggs in their hosts' bodies, which would explain the hosts' bloated appearance and the multiple poison headcrabs which cover them. It should be noted that Poison Zombies cannot be cut in half.

Tactics
Poison Zombies can take a lot more damage than other zombies (roughly 300%), and have better attack capabilities. Thankfully, Poison Zombies are rarely encountered.

When facing a Poison Zombie at close range, move around so you don't make an easy target for the Poison Headcrabs that the zombie will attempt to throw at you. Normally there are 2 or 3 riding headcrabs. When a thrown Poison Headcrab comes in contact with you, your health points will drop to 1 but will gradually increase by 10 as your HEV Suit administers an antidote from the poison. Therefore, try not to crowbar thrown headcrabs as they come in. Additionally, try to gain some distance because if you are too close, the headcrabs will jump off on their own.

The most effective weapon against Poison Zombies is fire: when hit, the zombie will set alight the headcrabs as well when dying. So a very good tactic is to grab a propane tank or gas canister, pop out of cover, light up the zombie then take cover before it throws headcrabs. It will die and take it's passengers with it without any damage to you.

If you can't use fire, grab a Pulse Rifle and alt-fire into the zombie. It will disintegrate with all passengers because as soon as it dies, all headcrabs will detach; however, they instantly touch the fusion orb as well, which means immediate death.

Because Poison Zombies tend to move quite slowly, and are a big target, it shouldn't be hard to hit them. Emptying a magazine into a Poison Zombie from an SMG1 or any other firearm will generally kill it. Explosives also work very well, such as SMG1 grenades and regular grenades. Don't use the rocket launcher, as there are better things it can be used for.

If you have no AR2 secondary fire, SMG secondary fire, grenades, or flammables to kill the zombie with, you can wait until all its headcrabs are thrown off and killed. The zombie should be a minimal threat without the hitch-hiking poison headcrabs on its back.

Like all zombies, a few well placed shots to the head will kill the controlling headcrab, and the zombie will collapse dead.

Trivia

 * There is no difference between the Poison Zombie and the Half Life 2 Beta "Fat zombie" Aside from the spine on it's back and the skin, this is easily notable by the feet