There are many mono-Black Commander options if you want to play Rats, but Marrow-Gnawer is by far the most powerful
You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast it
Card Name Mana Cost Type Legendary Creature Human Noble Wizard Rarity Rare rules Text When Joshua enters, discard up to two cards, then draw that many cards., : Exile Joshua, then return it to the battlefield transformed under its owner's control
Thats a boring spec, though, and its the Antiquities version that really gets me excited
Elite Fourum Going to Japan for the first time
If a card or token enters as a copy of a permanent, the new permanent isn't kicked, even if the original was