Boss Battle was a gamemode for Call of Duty: Infinite Warfare Zombies available in the Halloween Scream event that allowed players to fight the respective bosses of each Zombies map, starting chronologically with Zombies in Spaceland. Players are able to fight the Aliens, Super Slasher, the Rat King, Crog-Zilla, Cryptid onslaught and Mephistopheles. Players will need to own the respective DLC packs to play the respective maps.
When the player starts a map with Boss Battles ready, the player will spawn in the Afterlife Arcade. They will have a total of three minutes to pick up any weapon available on the wall of weapons and any perks with the 20,000 point balance. Depending on each weapon depends on its price, ranging from 2,500 points to 5,000 points. Once the player is ready, they can interact with the door used to return the player to the map or wait for the timer to run out. Once it is out or the player goes through the door, they will be brought to the boss fight of the respective map.
Inside the boss fight, there is a timer on the top left of the screen. This indicates how long the player is in the boss fight. The timer will stop once the whole boss fight is complete and the boss has finished their death animation. The game will automatic end and return the player back to the pre-lobby menu and be rewarded with a certain amount of XP and Keys. The fastest time the player achieves in completing a boss fight will be updated to the player's barracks on the map records.
From October 13th, 2017 to October 16th, 2017, Zombies in Spaceland and Rave in the Redwoods were available for play for Boss Battles, under the taglines Aliens! and Super Slasher respectively. Shaolin Shuffle and Attack of the Radioactive Thing, under the taglines The Rat King and Crog-Zilla respectively were available for play from October 20th, 2017 to October 23rd, 2017. Finally, both boss fights from The Beast from Beyond, under the taglines of Cryptid Fight and Mephistopheles respectively, was available from October 27th, 2017 to October 30th, 2017.