I'll add on a follow-up post with more technical details once I know them, but for now I hope this helps you assess the battles you see during spoiler season
Halo Fountain : A token generator, card draw, and a late game alternate win condition
Expect to face first-turn losses or to be locked down and unable to do anything in your turn thanks to unique pairings in this format
Before the release of the base set of Scarlet and Violet, the majority of rare cards had just one black star, regardless of what level of rarity they were One Black Star Weve already shown you this, as you can see from the image above
I highly recommend you open this deck on the Dueling Nexus yugioh deck builder
I rank the partner with commanders both by how useful they are alone, and how powerful they become when combined