Had an interesting disagreement during a recent game. I had Phage the Untouchable on the field. One of my opponents used Enslave on it to take control.
The disagreement ensued, because I said that he then lost the game. My reasoning was that when a creature is enslaved or taken control of, it technically leaves the battlefield, then comes back into play on the enslaver's side of the board. I know with other creatures, when they are taken control of, they then have "summoning sickness" again since they were not under that player's control for a full turn. He said that Phage doesn't leave the battlefield, she just switches sides.
Who was correct in this instance?
Since we couldn't agree, and couldn't get a proper ruling, the turn was ret-conned and he enslaved another creature I had which was It that Betrays. When he hit me with ITB, I gave him Phage and he lost anyway (we found that ruling on this forum).
I tried searching through the MTG official rules, and through this forum for a few hours, before deciding it was best to just make a thread, so we had an answer for the next time we play.
Notes: Phage's name fixed for tags to work. You need to write the full name for it to work.
Enslave doesn't cause the creature to leave the battlefield, just change ownership so they wouldn't lose the game. It would be the same with threaten effects It that Betrays dose take a creature that left the battlefield and put into the graveyard onto the battlefield under their control so they would lose for that one.
Your opponent was right. An enters-the-battlefield ability (such as Phage's) doesn't trigger if a player gains control of that permanent from another player, whether by Enslave or otherwise (C.R. 603.6a) (see Risky Move for an example of an ability that does trigger this way).
Note that gaining control of a permanent is a continuous effect (C.R. 611.1), not a one-shot effect, two of which are exiling a permanent and returning it to the battlefield (under C.R. 610.1), and that such a continuous effect is "continually and automatically performed by the game" (C.R. 613.4), since it's part of the layer system (C.R. 613.1b).
The disagreement ensued, because I said that he then lost the game. My reasoning was that when a creature is enslaved or taken control of, it technically leaves the battlefield, then comes back into play on the enslaver's side of the board. I know with other creatures, when they are taken control of, they then have "summoning sickness" again since they were not under that player's control for a full turn. He said that Phage doesn't leave the battlefield, she just switches sides.
Who was correct in this instance?
Since we couldn't agree, and couldn't get a proper ruling, the turn was ret-conned and he enslaved another creature I had which was It that Betrays. When he hit me with ITB, I gave him Phage and he lost anyway (we found that ruling on this forum).
I tried searching through the MTG official rules, and through this forum for a few hours, before deciding it was best to just make a thread, so we had an answer for the next time we play.
Note that gaining control of a permanent is a continuous effect (C.R. 611.1), not a one-shot effect, two of which are exiling a permanent and returning it to the battlefield (under C.R. 610.1), and that such a continuous effect is "continually and automatically performed by the game" (C.R. 613.4), since it's part of the layer system (C.R. 613.1b).
See also this thread.
EDIT (Sep. 24, 2019): Correctness edit.