Right now, you can book roundtrip flights from a whole bunch of US cities to places like London, Paris, Amsterdam, Dublin, Barcelona, and over a dozen other international destinations WOW flies to between now and May 15, 2018 for literally hundreds of dollars less than you would normally. In fact, after a few quick searches we were able to find roundtrip flights from New York to Paris for $225, roundtrip flights from Los Angeles to Amsterdam for $250, and roundtrip flights from Boston to Reykjavik for $165. The cheapest flights we could find on any other airlines for the same travel dates were $389, $728, and $441, respectively. In other words, this is a real steal of a deal.
To get in on it, simply enter WOWXMAS in the promo code field while searching for flights on any route, and look for preferred outbound and and return dates. Since the promo only applies to select travel dates depending on the route, it may require some back and forth searching to find a particularly great fare, but you should be able to find something if you spend a few minutes looking. You'll also need to book before 6:59pm on December 23, when the promotion expires.