Historical Rules · 29 September 2017
Rule 702.25a
Official source text from the 29 September 2017 Rules release
Phasing is a static ability that modifies the rules of the untap step. During each player’s untap step, before the active player untaps his or her permanents, all phased-in permanents with phasing that player controls “phase out.” Simultaneously, all phased-out permanents that had phased out under that player’s control “phase in.”