If I steal one of my opponent's critters with {Act of Treason} then flicker that creature will I get to keep him after the end of turn?
Yes.
Quote from: Testset on February 11, 2013, 11:15:22 AM
You keep it indefinitely.
RESOLVED
Or rather till the end of that game, upon which you should return it to its owner and thank them for the use of it.
Or
It dies.