Robe of Stars — ruling 1

Phased out permanents are treated as though they don't exist. They can't be the target 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.

Robe of Stars — ruling 2

Notably, this means you cannot equip Robe of Stars to another creature while it is phased out. If you activate the Astral Projection ability of an attached Robe of Stars in response to the equip ability, Robe of Stars will be phased out before the equip ability resolves and will not be moved.

Robe of Stars — ruling 3

As a creature is phased out, Auras and Equipment attached to it (including Robe of Stars) also phase out at the same time. Those Auras and Equipment will phase in attached to the creature they were attached to when they phased out.

Robe of Stars — ruling 4

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 {T} during that turn. If a permanent had counters on it when it phased out, it will have those counters when it phases back in.

Robe of Stars — ruling 5

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

Robe of Stars — ruling 6

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.

Robe of Stars — ruling 7

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

Robe of Stars — ruling 8

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

Robe of Stars : règles, fonctionnement et interactions (MTG)

Robe of Stars is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Equipped creature gets +0/+3. Astral Projection — : Equipped creature phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.) Equip

How it works : Robe of Stars

Original English text — Wizards of the Coast / Scryfall

#1July 23, 2021· Wizards of the Coast
Phased out permanents are treated as though they don't exist. They can't be the target 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.
No other card is named in this ruling.
#2July 23, 2021· Wizards of the Coast
Notably, this means you cannot equip Robe of Stars to another creature while it is phased out. If you activate the Astral Projection ability of an attached Robe of Stars in response to the equip ability, Robe of Stars will be phased out before the equip ability resolves and will not be moved.
No other card is named in this ruling.
#3July 23, 2021· Wizards of the Coast
As a creature is phased out, Auras and Equipment attached to it (including Robe of Stars) also phase out at the same time. Those Auras and Equipment will phase in attached to the creature they were attached to when they phased out.
No other card is named in this ruling.
#4July 23, 2021· Wizards of the Coast
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.
No other card is named in this ruling.
#5July 23, 2021· Wizards of the Coast
An attacking or blocking creature that phases out is removed from combat.
No other card is named in this ruling.
#6July 23, 2021· Wizards of the Coast
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.
No other card is named in this ruling.
#7July 23, 2021· Wizards of the Coast
Any continuous effects with a “for as long as” duration, such as that of Mind Flayer, ignore phased-out objects. If ignoring those objects causes the effect's conditions to no longer be met, the duration will expire.
No other card is named in this ruling.
#8July 23, 2021· Wizards of the Coast
Choices made for permanents as they entered the battlefield are remembered when they phase in.
No other card is named in this ruling.
#9July 23, 2021· Wizards of the Coast
If an opponent gains control of one of your creatures, that creature phases out, and the duration of the control-change effect expires before it phases back in, that creature phases in under your control as that opponent's next untap step begins. If they leave the game before their next untap step, it phases in as the next untap step begins after their turn would have begun.
No other card is named in this ruling.