Oddly enough the Mat isn’t a Next Challengers themed Mat.

The Event:

On July 19th-20th, Players will play in a Single Elimination Tournament with their Decks, which must contain 20 or more cards from NECH. (Your Extra Deck doesn’t count to towards this.)

The Mat:

Yes, there’s a Manga Elemental HERO and Masked HERO Mat with Neos and Divine Neos.

The winner of the above tournament gets one of these mats. The other mat is to be raffled off to a random participant.

Source:

http://www.yugioh-card.com/japan/event/nech/