They are usually exclusive prizes from high-level competitive events such as Pro Tours, Nationals, or special invitationals.
If you have activation cost reduction like Heartstone, then Palladium Myr can go infinite with Voltaic Construct
If that happens, it's just the new color, not that color and colorless
Does that all seem right?
Definitive information about card rarity was publicized through card lists in The Duelist
These cards serve valuable utility in Dimir reanimator decks in Legacy, which use blues unmatched stack interaction with blacks hand disruption and Reanimate, which is trivial to set up with pieces like Entomb or Troll of Khazad-dm, or even targeting yourself with Thoughtseize