This is then known as the Duelist's Deck Master. These Deck Masters are not classed as being on the field and stay face-up next to the player until the player decides to Special Summon it to his/her side of the field. The Deck Master's effect(s) are still active while not being played on the field.
If this were to become a real-world mechanic, it would be similar to an Extra Deck card; the differences being that the card is face-up and can be used and played of itself (doesn't require special summoning methods). It is however not kept in any known "Zone", but is apparently still part of the game even when not Summoned.
- This can be directly compared to Magic the Gathering's Commander play style, where you select a single Commander that can be summoned like any other monster but resides separately from the main game itself (due to other cards having similar states in other styles, the area was given an official name of the "Command Zone").
The Deck Master can be Special Summoned at any time during the Duel. Each card has its own effect as a Deck Master.
If a player's Deck Master is destroyed, he/she loses the Duel. If a player's Deck Master is Tributed by a card effect to Special Summon another monster or used as a Fusion Material Monster or can otherwise be immediately replaced such as by the effect of "A Deal with Dark Ruler", the monster that is Special Summoned next becomes the player's new Deck Master.
If multiple Deck Masters are Tributed, used as Fusion Material Monsters, or has an ability to special summon a new monster upon being destroyed, the Special Summoned monster is treated as the Deck Master for all of the players the original monsters belonged to.