Commander Masters is the first set in the Masters series to focus on Magic: the Gathering's ultra-popular Commander format. Like Commander Legends before it, the Commander Masters set is a complex and elegant blend of booster draft Limited and the chaotic fun of multiplayer. This means that Wizards of the Coast had to carefully choose which cards to put in Commander Masters for draft and reprint purposes alike, and that even meant changing card rarities, too.
Source：https://www.cbr.com/mtg-commander-masters-rarity-upshift/
