Specifically, will it be legal for the Warsaw Kotei? Is there a defined rule somewhere?

3 hours ago, HamHamJ2 said:

Specifically, will it be legal for the Warsaw Kotei? Is there a defined rule somewhere?

https://www.fantasyflightgames.com/en/op/l5r-lcg/kotei/ would normally have it, but has not been updated yet. I would ask the organizers of the Warsaw Kotei.

The rule for Thrones was immediately upon release for everything but Premier tier events, and eleven days for Premier events.

It's definitely something you should have an answer on soon!

This is covered in the Tournament Rules document, found here , under Legal Products.

The relevant bit is:

For Relaxed and Formal events, all product is legal in North America upon the product's official release. For Premier events, all product is legal in North America 11 days—typically the second Monday—after the product's official release. Official dates will be updated on the Product Legality page on our website (https://www.fantasyflightgames.com/en/op/legality/). Players outside North America should check with their organizer to determine which products are tournament legal.

So you need check with the organizers (it tends to be based on the local availability).