Raids are a real-time cooperative dungeon played by 2 users. Each entry cost a certain amount of Meat.
There are 3 different Raids that you can participate in, and there are 4 different Bosses you can fight, each getting progressively harder than the last. The harder the boss, the better the reward.
This Raid Boss is unlocked after clearing the Desert Scenario.
Ruler of Mana
Ruler of Mana can be accessed once you have cleared all stages of The Void, Path of Rage, and Road to Ruin.
Guardian of the Ruins
To access Guardian of the Ruins you need to complete Episode 1 of Kalard Chronicles.