When a player planeswalk into a plane, the top card of the planar deck is put there, and when the player planeswalk away from the plane, the top card is put at the bottom of the planar deck is then replaced by the next top card
(2022-06-10) If the opponent to your left chooses to copy Barroom Brawl but not change its targets, both targets will probably be illegal as the copy tries to resolve (at a minimum, both targets would have to survive and switch controllers in response to still be legal targets for the copy), and the player to their left will not be able to copy it
Shaddoll, Tellarknight and Star Seraph would have strong impacts on the metagame, taking multiple tops in various regions World Championship Qualifiers 2014
Galaxy-Eyes Afterglow Dragon
But it also enhances the ability of all-in combo decks to power out a winning line as early as turn one, posing an obvious threat to any other style of deck