The piercer is one of the rarest techniques for opening the head of a cigar.   Almost any pointy, sanitary instrument will do the job - including the back of a wooden match stick.  The objective is to pierce the cigar cap one or more times so the cigar will draw.  The drawback of using such a small opening is that tar, nicotine and moisture can accumulate at the openings and effect the flavor of the cigar.  The benefit of the piercer is that it can be preferred by people who like to smoke their cigars more slowly and draw less smoke.  In addition, some very enthusiastic smokers have been known to skewer their nub and use the piercer as a handle.