An attacking or blocking creature that phases out is removed from combat.

Phasing out doesn't cause any "leaves the battlefield" abilities to trigger. Similarly, phasing in won't cause any "enters the battlefield" abilities to trigger.

Permanents that phase out as The Phasing of Zhalfir's first and second chapter abilities resolve don't phase in during their controllers' untap steps while the Saga is on the battlefield. After it leaves the battlefield, they will phase in during their controller's next untap step as normal.

Choices made for permanents as they entered the battlefield are remembered when they phase in.

Phased-out permanents are treated as though they don't exist. They can't be the targets of spells or abilities, their static abilities have no effect on the game, their triggered abilities can't trigger, they can't attack or block, and so on.

As a Saga with read ahead enters the battlefield, its controller chooses a number from one to that Saga's greatest chapter number. The Saga enters the battlefield with the chosen number of lore counters. Neither choosing the number nor putting the counters on the Saga use the stack, and neither can be responded to.

Any continuous effects with a "for as long as" duration, such as that of Extraction Specialist, ignore phased-out objects. If ignoring those objects causes the effect's conditions to no longer be met, the duration will expire.

As a permanent is phased out, Auras and Equipment attached to it also phase out at the same time. Those Auras and Equipment will phase in at the same time that permanent does, and they'll phase in still attached to it.

Normally, permanents phase back in during their controller's untap step, immediately before that player untaps their permanents. Creatures that phase in this way are able to attack and pay a cost of during that turn. If a permanent had counters on it when it phased out, it will have those counters when it phases back in.