You can already create your own custom banlists for existing cards using https://duelistsunite.org/site/custombanlist/ but I find the website to be a bit confusing and it does not work for custom cards. However, you can …
A new tool for YGO Omega exists which you can use to create custom cards. This guide will show you how.
Download OmegaDEX from here: Release OmegaDEX · Lyris12/DataEditorX · GitHub
As of writing this guide, only the …