This clever combination turns a seemingly defensive enchantment into a self-mill engine by leveraging the targeting restriction of Reconnaissance. Because Reconnaissance's ability costs zero mana and can be activated as many times as you like, you can repeatedly target the attacking Cephalid Aristocrat. Every single time you declare Cephalid Aristocrat as the target of that ability, its triggered ability goes on the stack to mill two cards. By holding priority and repeating the process, you can mill your entire library on command right from the combat phase.