The Mexican Fiesta is an event released as part of the Mexican Fiesta (Update) on 10 September, 2015. It involves completing tasks with special MX weapons and MX gear to complete the tiers. It has a total of 15 tiers in all.
Mexico celebrates (Día de la Independencia) Independence Day on 16th of September. Hence, some weapons that were introduced in this event have the word "freedom" in their names.
In modern mexican wrestling (Lucha Libre), wearing masks that cover most parts of the head, hiding their identity, is pretty common and most wrestlers wear different kinds of masks.
In Mexican Wrestling, masks are colorfully designed to evoke the images of animals, gods, ancient heroes, and other archetypes, whose identity the wrestler takes on during a performance.
This event is widely regarded as the first event that indirectly required you to pay in order to complete the event, in the sense that it was near impossible to complete it without purchasing one of the bundles DLE released along with the event. Many players dislike this event immensely, and refer to it from time to time as one of the worst events ever released.