You can't flip them in Shiko decks, if you are making token copies of them, but I think getting their ETB abilities when they come into play is enough value
Red and green are the best, and for red, the reasons include cards weve already mentioned: Dockside Extortionist and Jeskas Will, but also Mana Geyser
Doctor Doom, King of Latveria hands your Villains connive, and connive means discarding cards, exactly what this 3/3 flier wants
I've played against many theft decks, and I run a fair bit of theft cards in my decks, and it often makes for a very fair play experience for the table
These cards have Magic backs, and you can write in the name of a double-faced card you have in your deck
While I may have lost some of you with that last point, it's safe to say that Nicol Bolas is a villain whose capabilities are only surpassed by his ambitions