TM Travel World explains how to take $80 off a Lufthansa flight purchased by August 11 for travel through December 30.
First, download a voucher.
Then make your booking on the Lufthansa website and
enter the number during the final step of the booking process. On the payment page, enter the voucher number into the field “Enter your Voucher:”. Be sure to click the “Apply Voucher and reduce Fare” link.
One voucher per reservation, so if multiple people are traveling you may want to book separately (to each get the $80 discount). A US credit card is required for the booking and travel must originate in the US (at a Lufthansa gateway, naturally).