Monster Zones (モンスターゾーン Monsutāzōn), formerly Monster Card Zones (モンスターカードゾーン Monsutākādozōn), are the Zones where monsters are placed on the field. In the future, there will be two types of Monster Zones, Main Monster Zones and Extra Monster Zones.
Cards on the field are treated as monsters if and only if they are in a Monster Zone. Monster Cards on the field are not treated as monsters if they are in other Zones (such as the Pendulum Zone or Spell & Trap Zone). Likewise, Spell and Trap Cards in the Monster Zones are treated as monsters (although Trap Monsters are treated as Trap Cards as well, so they also require a Spell & Trap Zone but are placed in the Monster Zone). Xyz Materials are not considered to be in a Monster Zone.
If all of a player's Monster Zones are occupied, then monsters cannot be Summoned to their side of the field, unless the monster is Summoned by removing monsters from the field. As such, a monster can be Summoned while all the Monster Zones are occupied by Tributing a monster(s) on that side of the field for a Tribute Summon or Ritual Summon, using a monster(s) on that side of the field as Material (Fusion, Synchro or Xyz), or by otherwise removing a monster(s) from the field for that Summoning procedure.
The player who performs the Summon or Normal Set, not the player who controls the Summoned monster, decides which Monster Zone the Summoned/Set monster is placed in. A monster can be Summoned/Set in any unoccupied Zone (unless the Zone has been rendered unusable by a card like "Ojama King"). The Zone into which a monster will be Summoned/Set is decided before the Summon negation window. Monsters cannot be moved between Zones, except by a card effect like "Senet Switch".
On game mats, Main Monster Zones are located in the upper-middle and are often colored brown. In future game mats, Extra Monster Zones will be located in the center of the field and are colored green.
- ↑ "Master Rule 3 Overview". Konami. http://www.yugioh-card.com/hk/howto/master_rule_3.php?lang=cn-t.