Onslaught Containment, also known as simply Containment is a limited-time mode introduced in Call of Duty: Black Ops Cold War Zombies during Season Two Reloaded. It is a variant of the previously introduced Zombies Onslaught mode, however instead of taking place on traditional multiplayer maps, it takes place on Gunfight maps. The mode was removed with the release of Season Three Reloaded. With the release of Season Five, Containment was added back with the additional map Nuketown '84.
Like Onslaught, Containment can be played with up to two players, and involves players completing Surges and Elite Surges. However, unlike the main Onslaught mode, the Dark Aether Orb is red and completely stationary.