Commander has the rule zero discussion. You sit down at a table and can talk about commanders/combos/cards you're unwilling to play against. This needs to be added to the play queue on Arena. Give me a box where I can type in the name of up to a few cards I don't want to see in an opponents deck and then have the matchmaker filter those decks out so I don't have to play against them. It would be invaluable data for wotc to see what the most filtered out cards would be and greatly increase the play experience for people who are sick of seeing degenerate play patterns on the other side of the screen.