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 Clone to return from exile to the battlefield as a copy of Phantom Steed.
When Clone enters the battlefield, its first ability triggers, exiling Phantom Steed until Clone 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 Clone 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.
Clone leaves the battlefield, ending its effect, causing Phantom Steed to return to the battlefield from exile.
Repeat from step 2.
This ingenious loop relies on a perpetual exchange of presence between Abdel Adrian, Gorion's Ward, Phantom Steed, and Clone. When Abdel Adrian enters the battlefield, it exiles Clone, which breaks the lingering exile effect holding Phantom Steed and lets Phantom Steed return to trigger anew. Phantom Steed promptly turns around and exiles Abdel Adrian, which in turn drops the curtain on Clone's exile and allows Clone to reappear as a fresh copy of Phantom Steed to restart the cycle. Because this bouncing act infinitely repeats, Abdel Adrian continually enters and leaves the battlefield to churn out an endless army of 1/1 Soldier tokens while blinking all your other nonland permanents along the way.