Ultimately, any mechanic that alters the fundamental rules of the game across all formats should be considered incredibly carefully, especially when it will drastically warp all future gameplay around a handful of new cards
If you made a new Ruby/Steel deck, you couldnt include the featured Belle, Beast, or Jafar cards as they would all mean youd have three ink colors in the new deck
You can pair this Ezuri with cards like Astral Cornicorpia, which adds mana equal to the number of charge counters on it, and then keep proliferating up those counters
As for what Reign of Jafar itself has in store, details are a little scarce at the moment
We've seen cards cut incorrectly, capturing the top and bottom from two cards, tears from factory machinery, and prints with misaligned plates