mtg are commander cards legal in standard Magic Arena Exclusive (Legal MTGA standard) : r/magicTCG Is Lions Eye Diamond Legal

Kaheera, the Orphanguard Kalonian Behemoth Kethek, Crucible Goliath Kezzerdrix Kona, Rescue Beastie Krakilin Krosan Beast Krosan Cloudscraper Krosan Colossus Laccolith Titan Lightning Reaver Loot, Exuberant Explorer Lovestruck Beast Lumbering Battlement

Here are a few options: Leave the physical card outside the game and use a labeled substitute card for while the card must remain hidden in your library or face down Sleeve your deck with fully opaque backs like Dragon Shield Matte sleeves

At first glance, Common Cause looks like a playable card

The target of Rex Nebula's ability will become a Vehicle artifact until end of turn