
Exile all creatures you control, then reveal cards from the top of your library until you reveal that many creature cards. Put all creature cards revealed this way onto the battlefield, then shuffle the rest of the revealed cards into your library.
Mass Polymorph has 3 printings, first in Magic 2011 (2010). EDHREC ranks it #9,267 among Commander cards. It appears most in Jace, Multiverse Architect decks (7,599 on EDHREC). 1 public deck on TCG runs it. It has 4 official rulings.
Deck counts from EDHREC.
Cards that show up in the same decks on EDHREC.