Available for purchase are booster packs and boxes, single-player prebuilt decks, the Illumineers Trove, card sleeves, and deck boxes with card art of Mickey Wayward Sorcerer or Tinker Bell Giant Fairy, and play mats featuring card art of Hades Double Dealer, or Rescue Rangers Away
[...] The metagame of Commander has largely been dictated by the collector marketplace, which itself is largely dictated by a card's demand in non-Commander settings"
Giving an MDFC creature a transform ability via something like Agathas Soul Cauldron is your only real route here, and that introduces a whole host of limitations
In the case of Relentless Rats, we had to look at the four card limit
Rare cards from Scarlet and Violet sets Even modern Scarlet & Violet sets feature valuable cards
Dualcaster Mage enters and targets Electroduplicate, making a copy of the spell