Astral Suppression

[The Nyx Avatar]

[Flash Flyer - Sakura]

This is an example of a floodgate, which I hope you know cuts off a certain game mechanic.

Granted, you can still Special Summon other monsters, but unlike Vanity's, this has no way of being removed, save for the usual MST and other things.

 

With that in mind, Xyz aren't as common as they were in the ZEXAL era, but do keep in mind that there are still a good amount of Decks that make Xyz.

Having this card out screws them over big-time, but they probably have ways to deal with it. 

 

I would advise having it blow itself up after a while, or you put a maintenance cost on it.

 

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Flavor-wise, this falls into the category of Non-Fusion Area and Discord (well, this one blew itself up after three turns).

[The Nyx Avatar]

I made it with that in mind. I noticed that Non-Fusion Area was a Continuous Trap that states "Neither player can Fusion Summon", Dark Highlander which states "Neither player can Synchro Summon."(although that one had more in its effect), but there was nothing for Xyz. So I made a Field Spell that states "Neither player can Xyz Summon". I didn't add anything else to the card. I figured it'd be simplistic in only preventing Xyz Summons, but decided not to add anything else to its effect that would make it unfair.

[Tinkerer]

I guess XYZ is ready for a "Non-fusion area" type card, but I believe you should change it to a continuous (if only because field spells are searchable).

I like how this card would increase playability of slower decks that don't use XYZs (steelswarm really needed that), but it can also be (ab)used in XYZ-using decks by playing it after XYZing. It also opens up the use of double cyclone as well.

Honestly, these issues probably only scratch the surface over how this card can be (ab)used, but I can't really say much else about it...