If Creeping Inn is attacking or blocking when it phases out, it is removed from combat.

Creeping Inn will phase in during its controller's untap step. It will be able to attack the same turn.

If an opponent gains control of Creeping Inn and it phases out and the duration of the control-change effect expires before it phases in, it phases in under your control as that opponent's appropriate untap step begins. If they leave the game before that untap step, it phases in as the next untap step begins after that turn would have begun.

Each Aura and Equipment attached to a permanent that's phasing out also phases out. They will phase in with that permanent and still be attached to it. Similarly, permanents that phase out with counters phase in with those counters.

While Creeping Inn is phased out, it's treated as though it doesn't exist. It can't be the target of spells or abilities, its static abilities have no effect on the game, its triggered abilities can't trigger, it can't attack or block, and so on.

When Creeping Inn phases in, it still remembers what cards were previously exiled with it.

Phasing out or phasing in doesn't affect which face of a double-faced card is face up.

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.