Arena needs new features to allow players to delete cards from their collection and also to decline to open offensive booster packs sometimes given as rewards.

There are now a rapidly growing number of unwanted cards and sets on Arena, which lacks the ability to opt out of adding these to your collection. There are several ways arena could support removal of this problem.

1) give players the ability to permanently delete cards and packs they don’t want.
2) better: let players blacklist sets with offensive (to them) content preventing them from seeing it in deck design and even suppressing card arts, pets and portraits their opponents use (assuming alternatives exist)
3) best: both of the above and add a feature to casual matchmaking inc. brawl where this flag blocks matching with players with blacklisted cards in their deck. This would reduce the frequent concessions one gets in brawl.

Seeing what people actually blacklist would give valuable feedback on card design and surface hard data about the damage to the magic brand being done by ill considered UB partnerships.

As an aside the intersection of standard window, fire design and UB means an in universe only format with a shorter rolling window would also be popular as there are now no slow low power formats.