Treasure Bags are consumable items obtained in Expert Mode and Master 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 deals damage to the boss receives one Treasure Bag upon completion. Treasure Bags are client-side and will despawn upon exiting the world.
In addition to the above, all Treasure Bags from Hardmode bosses (except Queen Slime's) have a 5% chance to contain a random set of developer items, meaning that each set has a 0.28% chance of being in a Hardmode boss Treasure Bag. 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.
In multiplayer, participation is based on damage dealt to the boss. Players who did not deal at least 1 point of damage to the boss will not receive a bag.
It is advisable to open bags on the ground in a quiet area if you have a full inventory as the delay in picking up the prizes can cause items to fall to other players.
Treasure yields are considerably higher in multiplayer - multiple bags are handed out, with each containing the entire reward of a kill, and drop rates on the boss's unique items are often doubled.
Trophies are not obtained from Treasure Bags. Instead, they are dropped separately from the boss itself.
The Moon Lord's Treasure Bag is the only one to include both more than two Expert mode items and no money.
Betsy's Treasure Bag is the only (obtainable) bag that does not have an Expert mode item. It is also (along with the Moon Lord's) one of the only ones to contain no money, replacing coins with Defender Medals.
The Lunatic Cultist, Ogre, and Dark Mage have sprites for a Treasure Bag, even though they do not drop one.
Unlike the Lunatic Cultist's Treasure Bag, the Ogre and Dark Mage do not have data assigned to their Treasure Bags, as attempting to hack in either one will cause them to disappear from the player's inventory instantly.
Queen Slime's Treasure Bag is the only hardmode Treasure Bag to not drop developer items.
!!Error: Invalid EICONS input!Additionally, it is the only Treasure Bag to not have the tooltip "Right Click to open"
Treasure Bags are referred to as "Boss Bag" in their Item IDs.