Flood tank form

The Flood tank form is a type of Flood pure form.

Description
Flood tank forms are not unlike the similar thrasher forms, encountered on Shield World 0459. Unlike the thrashers (and all other combat forms), the tank form does not consist of a host controlled by a pod infector, but is instead a type of Flood pure form. Like all pure forms, the tank form is composed of raw Flood biomass, created only when an outbreak reaches the Coordinated Stage. The Flood pure form is capable of mutating whenever it chooses to match the situation at hand, resulting in the tank form being created when under heavy fire.

When a stalker form is cornered or confronted with well-armed opponents, it will often undergo a rapid transformation into a tank form to better defend itself. Most of the stalker's body mass shifts to the frontal body section, forming a muscular torso. The rear limbs are augmented with muscle to serve as legs, while the forelimbs become bulkier and rapidly extrude bone structures to form blade or club-like appendages. In this state, the tank form is more resistant to conventional weaponry and possesses more devastating melee capabilities, but moves at a far slower pace.

Tank forms are quite slow in comparison to combat forms, but they make up for it with relative resilience and devastating melee attacks. They can run on all fours for a short period, allowing a short burst of speed to overtake a target. Tank Forms can spew a torrent of Infection Forms from their 'mouth' as a form of short ranged attack, or in order to infect nearby corpses.

On rare occasions, a Tank Form will mutate directly to/from a ranged form.

History
Flood tank forms saw use in the Forerunner-Flood war. Following the firing of the Halo Array, Flood tank forms were held aboard Halos Installation 04 and Installation 05 for research and testing. In 2552, many tank forms were able to break containment on Installation 04, and were let loose onto the ring. Several found their way to the ice canyons surrounding the ring's control room, where they were engaged the Covenant and the ODSTs of Fireteam Raven. One tank form was almost able to kill the team, before it was killed by John-117. The fireteam continued to engage tank forms across the ring, before its eventual destruction.

Following the large Flood outbreak on Installation 05 and subsequent Fall of High Charity, the Flood had billions of beings' worth of mass with which to create an army. They began creating massive amounts of new pure forms, including tank forms. Many were encountered by UNSC forces during the Battle of Voi, carried by the Indulgence of Conviction. Later on, tank forms were used by the Gravemind as puppets through which to speak to John-117 and Thel 'Vadam to secure a temporary truce to kill the Prophet of Truth and prevent the firing of the rings. These tank forms assisted the human and Sangheili warriors, guiding them through the loyalist Jiralhanae before turning on them once the crisis was averted. Many Flood tank forms resided within the remains of High Charity following its crash on Installation 00 and attempted to stop John-117 in his mission to rescue Cortana, before later being dropped onto the newly-constructed Installation 08 to to stop the attempted firing of that ring.

Gameplay

 * When shot, the Tank Forms usually cover their faces (which are usually their weak spots) with the bony plates on their arms. Try to avoid shooting the plates as they don't take any damage.
 * Tank Forms are usually very slow except for the moments where they charge. Try to flank them, but do not move away too much as it may transform into a Ranged Form or Stalker Form to chase after you or to shoot from a distance.
 * They are very resilient to most firearms, although plasma seems to affect them more than normal ballistic weaponry. Melee weapons like the Energy Sword and the Gravity Hammer and most power weapons work very well against them.
 * There is an easy way to kill a Tank Form other than using an Energy Sword. If you just melee him in between the two tentacles on his head he will die instantly, although it can be hard to hit it in the kill spot if it's swinging its arms and moving around.
 * One direct hit from Flamethrower is sufficient to kill it. Igniting it on fire with Incendiary Grenade also can kill him almost instantly.

Production notes

 * The Flood Juggernaut, a Flood Form cut from Halo 2, was an early concept of the Halo 3 Pure Form. The Sharquoi, another deleted species from Halo 2, may have served as the inspiration for the Tank form. This is further proven by a piece of concept art in The Art of Halo 3 that appears to be three Flood Juggernauts engaging several Marines and the Master Chief in combat.
 * The design of the Tank Form is reminiscent of the Drinniol (or "Hulk") enemies from Marathon, one of Bungie's earliest games.
 * When a Tank Form takes a hit from a Gravity Hammer, the spike platform can be seen for a few seconds when the Tank Form jumps up.

List of appearances

 * Halo 3
 * Halo Legends
 * Origins
 * Halo: Combat Evolved Anniversary
 * Terminals
 * Halo: Fireteam Raven