Expert Gameplay FAQ: Summon Negation Window

The Summon negation window is an unofficial term for the activation timing of cards that negate the summon of a monster, such as "Solemn Warning", "Solemn Judgment", "Black Horn of Heaven", "Evolzar Laggia", "Thunder King Rai-Oh", "Royal Oppression", etc.

This timing is before the "Summon response window". If the monster's summon was negated in the "Summon negation window", there will not be any "Summon response window" afterwards.

Only cards that negate Summons can start the chain during this window, so "Mystical Space Typhoon" cannot be activated at the start of the "Summon negation window", but it can be activated as Chain Link 2 if "Royal Oppression" was activated first. Cards like "Bottomless Trap Hole", "Trap Hole", etc. that response to the summon of a monster cannot be activated during this window; they can only be activated in the "Summon response window".

In the "Summon negation window", due to Fast Effect Timing, the turn player can activate cards that negate the summon of a monster before the opponent can, such as "Solemn Warning", to negate the summon of his own monster, though this is almost never seen in normal play.

Example
Player A declares he is going to summon "Black Luster Soldier - Envoy of the Beginning".
The "Summon negation window" (or timing) is open now, and player B can activate cards that negate the summon of a monster, such as "Solemn Warning", "Solemn Judgment", "Black Horn of Heaven", etc.

If player B chooses to activate one of such cards, "Black Luster Soldier - Envoy of the Beginning's" summon will be negated, and it will not be considered to have been "successfully summoned".

If player B passes without playing any such cards, "Black Luster Soldier - Envoy of the Beginning" will be successfully summoned. Now the "Summon negation window" is closed and the "Summon response window" is opened.

There is only one chain in the "Summon negation window". After that, no card that negate the summon of a monster, such as "Solemn Warning", can be activated.