It’s based on a infamous pair. Who are more then willing to not play fair.

The next major event in Duel Links is playing against the Paradox Brothers, Para and Dox (known as the Labyrinth Brothers in Japan, named Mei and Kyuu (essentially Laby and Rinth).)

And their Key Cards are:

• Kazejin
• Sanga of the Thunder
• Gate Guardian
• Suijin

Source: V Jump