Can Kaiser Colosseum stop Stardust Dragon from special summoning?

Answer 1

According to Kaiser Colosseum's effect, the controller's opponent cannot have more monsters on the field than the controller. For example, if you have one monster on your side of the field, and your opponent also has one then your opponent cannot perform any Summon that would allow him/her to obtain more monsters than you control.

In answer to your question, Stardust Dragon could only be re-Special Summoned onto the field if the amount of monsters on that particular side of the field would not exceed the controller of Kaiser Colosseum (if the controller was the opponent). This is because Stardust Dragon still occupies one Monster Card Zone.

For example, if you control one monster and a face-up, active Kaiser Colosseum, and your opponent also controls one monster and a Stardust Dragon in their Graveyard due to its negation effect, your opponent cannot Special Summon Stardust Dragon onto the field at the End Phase. This is because, your opponent would control more monsters than you do.

If you were referring to the Synchro Summoning of Stardust Dragon, your opponent could only Synchro Summon it if the amount of monsters on your opponent's field remain equal to or less than the amount on your field after the Synchro Summon.

For example, if you have five monsters on your side of the field, and your opponent has two, if the monsters are appropriate, your opponent can Synchro Summon Stardust Dragon to their side of the field, as the amount of monsters on their side of the field would still be less than your side.

However, in another scenario, your opponent has five monsters on your side of the field, and you only have one. You activate Kaiser Colosseum; however, the monsters on your opponent controls are unaffected as it was activated after they were placed on the field. In this scenario, unless the Synchro Summon of Stardust Dragon would require all five of the monsters on their side of the field, they could not perform the aforementioned action. This is because, if they used four monsters or less, the amount of monsters they control would exceed yours (Stardust Dragon still occupies one Monster Card Zone. Therefore, if your opponent were to use four monsters, they would end up with two monsters after completing the Synchro Summon, which would exceed your amount).

For more information regarding the rulings of Kaiser Colosseum, click on the "Related Link" below.