Energy is used for battles and missions, and recovers over time. It is displayed as 3 colored bottles in the upper left of the UI.
1. World Energy: 1 point recovered every 10 mins. Used for PvE.
2. Raid Energy: 1 point recovered per hour. Used for raids and PvP battles with other players.
3. Giant Corrupted Energy: 1 point recovered every 4 hours. Used for Giant Corrupted Battles with your alliance.