Aether Raids

Aether Raids is a game mode in Fire Emblem Heroes which was introduced in version 2.11.0.

Overview
The Aether Raids mode shares some similar principles with Arena Duels, where the player's team has to defeat a team built by another player and controlled by AI in an offensive battle to earn scores and increase ranking in exchange for rewards, or build their own team to defend against another team to reduce the deducted scores. However, the major difference in Aether Raids is that teams on both sides have the assistance of structures which can be built and placed on the map to create situations for the battle. A battle is also limited to seven turns for a successful attack or defend.