Treasure Bags are consumable grab bags obtained in Expert Mode as a reward for defeating bosses. Its contents depend on the boss it comes from. It is opened by either right-clicking it inside the inventory or using it while it is in your hand. In multiplayer, each player that is online at the end of the battle receives one Treasure Bag each. Treasure bags are client-side and will despawn if you exit the world.
Each Treasure Bag contains the boss's usual drops from normal mode, and some contain Expert Mode-exclusive items (green-highlighted items below), Revengeance Mode-exclusive items (red-highlighted items below) or Death Mode-exclusive items (purple-highlighted items below).
Slowly fills the Rage Meter over time, boosts damage by 10% while under the Absolute Rage buff, increases the chance of the Absolute Rage buff being inflicted on the player, and increases the damage rage mode does.