Any Outer Domain can be re-seized. Outer Domain can be seized only if there are no defensive buildings in it, such as Towers, Magic Towers and Fortifications.
If seizure is a result of Joint Attack the domain will go to the attack initiator.

Cities cannot be seized.

Tunnel Closing.
EXAMPLE:
Player1, a Pit’s owner, began Pit’s Tunnel closing.
If Player2 seizes the Pit while the Tunnel is closing, the Tunnel will continue closing anyway.

EXAMPLE2:
Player1, a Pit’s owner, began Pit’s Tunnel closing.
Player2 launched a Re-Seizure attack.
Player1, having a presentiment of defeat, refuses the Pit; in this case the Tunnel closing will stop.