Standard, Commander, Modern, Pioneer, Timeless, Historic, Vintage, Legacy, and other formats are all made up of different sets with their own rules on which sets are considered legal in that format
Which one you choose will of course be up to the specific needs of the current game, but it's hard to see a situation where you won't want one or the other
So you want to see cards that transform into Planeswalkers or make use of mechanics that you couldnt do on a single face
It used to be that only instants could be played at any time during a game of Magic
While this card remains a long shot to make the list of the most valuable cards in Cosmic Eclipse for some time, its art stands out as one of the best in the set
While this card is a "Yellow Cheeks" variant, it's still a very rare card that is highly sought after by collectors