Treasure Bag

Treasure Bags are consumable items 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, along with at least one Expert Mode-exclusive item (orange-highlighted items below).

All Thorium Boss Bags additionally have a 3.33% chance to contain one random set of developer items.

Event Bosses
The Dark Mage's Treasure Bag drops with a 100% chance during Tier 1 of the Old One's Army, and with a 25% chance in Tier 3. The Ogre's Treasure Bag drops with a 100% chance during Tier 2 of the Old One's Army, and with a 25% chance in Tier 3.

Developer items
In addition to the above, all Treasure Bags (excluding the Lunatic Cultist Bag) have a 3.33% chance to contain a random set of developer items, with a 5% chance in Hardmode to obtain Phonic Wings alongside the random set. Obtaining a Treasure Bag in an Expert world, then opening the bag in a Normal world will retain the Treasure Bag's chance to yield developer items.
 * Brutal set
 * Cataclysmic set
 * Chunky set
 * Danny's Lament set
 * Ghastly set
 * Grand Thorium set
 * Halcandran set
 * Mr. Universe set
 * Wild set