Whenever damage from a Rakghoul causes a non-Droid, non-Rakghoul to be discarded, each player rolls a die. If it's a tie, each player rolls again until a player rolls higher. The player who rolls higher takes 1 30/3/2 Infected Rakghoul Subordinate with "Critical Hit 1" and puts it into the Ground or Character arena under his or her control.
If all units in an arena are infected Rakghouls, each player can't control that arena.