The Battle Zone (バトルゾーン, Batoruzōn) are 3 new Zones only used by Battle Units, located behind the Spell & Trap Zone.
When the conditions are met and/or the costs have been paid, a player may place a Battle Unit from wherever into one of their Battle Zones. While in the Battle Zone, Battle Units are only considered as Battle Units and cards on the field. The Battle Unit Effect of that card is also applied rather than its Monster Effect.
While there is a limit of placing 3 Battle Units into your Battle Zone, there is also a limit of the total Offense Points and Guard Points of the Battle Units in your Battle Zone. The maximum total of Offense Points of the Battle Units in your Battle Zone is 10, while the maximum total of Guard Points is 20.