Today’s Unfinity announcement included the introduction of the acorn watermark as the new method to distinguish what were previously silver-bordered cards.
We will be updating the rules for card legality to make the acorn symbol equivalent to silver-borders; they’re not allowed by default (but should be encouraged among playgroups!)
We considered allowing them – Commander is not a tournament format, so philosophically it aligns with Mark Rosewater’s points about un-cards – but while some of the classes of cards that get an acorn symbol would be fine (art-based abilities, for example) others are not (physical dexterity cards) and further trying to split would descend to specific card lists. Those might be viable as an optional addition, but not something we would look to make default.
Set looks like a ton of fun, though. Looking forward to it! As always, you’re welcome to join us on the RC Discord server to chat about it.