When control of two permanents is exchanged, if those permanents are controlled by different players, each of those players simultaneously gains control of the permanent that was controlled by the other player. If, on the other hand, those permanents are controlled by the same player, the exchange effect does nothing.
February 5, 2021 · Kaldheim
If one or both creatures instructed to fight are no longer on the battlefield or are no longer creatures, neither of them fights or deals damage. If one or both creatures are illegal targets for a resolving spell or ability that instructs them to fight, neither of them fights or deals damage.
April 27, 2018 · Dominaria
If a creature instructed to fight is no longer on the battlefield or is no longer a creature, no damage is dealt. If a creature is an illegal target for a resolving spell or ability that instructs it to fight, no damage is dealt.
September 30, 2016 · Kaladesh
To play a card means to play that card as a land or to cast that card as a spell, whichever is appropriate.
May 1, 2014 · Journey into Nyx
If the effect of a static ability regenerates a permanent, it replaces destruction with an alternate effect each time that permanent would be destroyed. In this case, “Regenerate [permanent]” means “Instead remove all damage marked on [permanent] and tap it. If it’s an attacking or blocking creature, remove it from combat.”
February 1, 2014 · Born of the Gods
If the effect of a static ability regenerates a permanent, it replaces destruction with an alternate effect each time that permanent would be destroyed. In this case, "Regenerate [permanent]" means "Instead remove all damage marked on [permanent] and tap it. If it’s an attacking or blocking creature, remove it from combat."
September 30, 2011 · Innistrad
If the effect of a static ability regenerates a permanent, it replaces destruction with an alternate effect each time that permanent would be destroyed. In this case, "Regenerate [permanent]" means "Instead remove all damage marked on [permanent] and tap it. If it's an attacking or blocking creature, remove it from combat."
June 17, 2011 · Commander 2011
Revealing a card doesn’t cause it to leave the zone it’s in.
April 1, 2011 · Duel Decks: Knights vs. Dragons
Revealing a card doesn't cause it to leave the zone it's in.
October 1, 2010 · Scars of Mirrodin
Revealing a card doesn’t cause it to leave the zone it’s in.
February 1, 2010 · Worldwake
Revealing a card doesn't cause it to leave the zone it's in.