March of the Machine

Invasion of Xerex // Vertex Paladin

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Xerex enters the battlefield, return up to one target creature to its owner's hand.

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When this Siege enters, return up to one target creature to its owner's hand.