When Phantom Steed enters the battlefield, its first ability triggers, exiling Abdel Adrian until Phantom Steed leaves the battlefield.
Abdel Adrian leaves the battlefield, ending its effect, causing Lumbering Battlement to return from exile to the battlefield.
When Lumbering Battlement enters the battlefield, it triggers, exiling Phantom Steed until Lumbering Battlement leaves the battlefield.
Phantom Steed leaves the battlefield, ending its effect, causing Abdel Adrian to return from exile to the battlefield.
When Abdel Adrian enters the battlefield, it triggers, exiling Lumbering Battlement and any number of other nonland permanents you control until Abdel Adrian leaves the battlefield and creating at least one 1/1 Soldier creature token.
Lumbering Battlement leaves the battlefield, ending its effect, causing Phantom Steed to return from exile to the battlefield.
Repeat from step 2.
Results
Infinite blinking of nonland permanents you control.