Devil Square is a PvE event where players fight waves of monsters to gain a lot of experience. As the event continues, monsters become stronger, so the difficulty increases. The more monsters you kill, the higher your chance to win. Players who survive and deal high damage receive good rewards, including a large amount of Zen.

To enter you need Devil Square Ticket, you can buy it or get as Reward. Also you can use for entering Devil's Invitation, which can be crafted in the Chaos machine: