(As of the 25th of April 2012, Priority is no longer an official term in the TCG. Priority of Ignition Effects has been removed, while other mechanics involving priority have been renamed "Fast Effect Timing".)
Priority (優先権, yūsenken) was defined as "A player's 'right' to be able to activate his/her effect, ensuring its spot on Chain Link 1." Priority did not allow players to automatically activate and resolve effects without a chain; it simply assures a card's activation (not resolution), and guaranteed a place on Chain Link 1. The chain resolved from the last Chain Link put in the chain to the first one.
Priority told who can activate an effect at any certain point in the game. Note that cards never had priority; it is the players who have priority. The Turn Player always started with priority.
Player B, now being the turn player, says he wishes to retain his priority to activate the effect of "Chaos Sorcerer". The Ignition Effect of "Chaos Sorcerer" then activates, targeting "D.D. Warrior Lady". The effect of "Chaos Sorcerer" is now Chain Link 1. Player A then activates his "Bottomless Trap Hole", since the Special Summon of "Chaos Sorcerer" was the last action to have resolved on the field. "Bottomless Trap Hole" is now Chain Link 2.
The chain now resolves in reverse:
- Chain Link 2: "Bottomless Trap Hole" resolves. "Chaos Sorcerer" is destroyed, and banished.
- Chain Link 1: The effect of "Chaos Sorcerer" resolves. "D.D. Warrior Lady" is now banished.
Always remember that Monster Effects, unless they specify otherwise, can have their effects resolved without being present on the field.
This is no longer in either the TCG, or OCG; the OCG ruling was changed on March 19, 2011, whilst the TCG ruling was changed on April 25th, 2012.
● Before revision The Ignition Effect of a monster can be activated at the timing a monster is successfully Summoned (including Flip Summon, Special Summon).
● After revision The Ignition Effect of a monster cannot be activated at the timing a monster is successfully Summoned (including Flip Summon, Special Summon).
The resolution of this chain works as follows:
- Chain Link 2: "Book of Moon", targeting "D.D. Warrior Lady" resolves, flipping "D.D. Warrior Lady" to face-down Defense Position.
- Chain Link 1: The Ignition Effect of "Chaos Sorcerer" tries to resolve, but since his target is now face-down, his effect disappears, because "Chaos Sorcerer" can only banish face-up monsters.
One can pass priority by simply stating "I pass priority".
Optional Trigger Monster Effects, like "Mobius the Frost Monarch", are not Ignition Effects, so their effect(s) can only be activated when the condition that triggers them was the last action to have resolved on the field. If the player activate them, then the priority will passed to the opponent.
Priority is also automatically passed when the Turn Player declares an end to any Phase.
Turn Priority normally cannot be ignored. However, if the opponent has a card that can be activated at a specific time, such as the Standby or Draw Phase of the opponent's turn, these cards can be activated, and the turn player cannot stop that due to the priority if he didn't have a card(s) to play at that time.
If the opponent plays a card before the Turn player claim priority, a replay can be demanded if the Turn player wish to claim his priority. To avoid this dispute, it is etiquette to ask the Turn Player if they would like to play a card during a respective phase before doing anything (since declining to play a card results in passing their Priority to the Opponent).