“Mythical Beast” Special Feature: Pendulum Monsters That Can’t Pendulum Summon!? They Develop The Game By Being In The Pendulum Zone And Using Spell Counters!! “Extreme Force” (which went on sale October 14th, 2017), includes the “Mythical Beast” theme which is based on making its moves using Spell Counters, while utilizing the Pendulum Zone! All of
Basically the Deck limitatons/rules for an ongoing official Character Deck event run by Konami. For more casual players interested in official rules like this.