Pretty much what it says, let’s go into details:
Basically the top ranking 250 Duelists of each period will get a chance at a sweet Rubber Mat. As well, 50 Duelists who played during that period will have the chance to earn it via a raffle/lottery.
When are the periods?
Periods:
August 1st, 2014 to September 30th, 2014
October 1st, 2014 to December 31st, 2014
January 1st, 2015 to March 31st, 2015
What are the mats? Well, their designs haven’t been announced yet.
Source:
https://twitter.com/touchxxKDT/statuses/486715888125476864
