Master Mode

Master Mode is an option that can be selected during world creation, and that can also be turned on through the difficulty slider in Journey Mode. It further increases the difficulty of the game beyond Expert Mode, as well as offering Master Mode-exclusive items. Like Expert Mode, Master Mode begins the moment the Master Mode world is created, and cannot be altered after that by the player outside of Journey Mode. Master Mode also drastically increases enemy health and damage.

Master Mode gives the player one more accessory slot, meaning that the player can have a total of 7 accessory slots after consuming the Demon Heart in Hardmode.

All Expert Mode content is also available in Master Mode. All Expert Mode AI changes also apply.

Master Mode introduces new items that can be collected by defeating bosses, such as Relics that can be placed to show off one's victories against bosses, as well as the Master Mode exclusive Pets/Mounts, which have a 25% drop rate.

General

 * Most enemies have roughly 50% more health, deal more damage and have 10% more knockback resistance than in Expert Mode (thus three times as much health and 20% more knockback resistance than in Classic Mode).
 * For example: Blue Slime stats are |  |
 * When entering Hardmode in Master Mode, enemies' health and attack power drastically increase (for example, the Blue Slime will have | ).
 * The following debuffs last 2.5 times (25% longer than in Expert ) as long when inflicted on players:

Bosses

 * Bosses in Master Mode have increased health. Each boss has their own health scaling factor for Master Mode.
 * Bosses gain 50% more damage to their expert values.

Player

 * Players will drop of their Coins upon death instead of 50% /.
 * Players gain an additional accessory slot that is only active while in a Master Mode world. This stacks with the Demon Heart, resulting in the maximum attainable slots to be 7.
 * Damage taken is reduced by of the player's Defense value instead of 50% /.

Master-exclusive items

 * Bosses drop "Master Mode"-exclusive items similarly to Expert Mode, but they also drop their Treasure Bag, which contains the Expert Mode-exclusive item/items of the boss. In Journey Mode, bosses killed while the difficulty slider is set to Master will drop Master Mode drops, regardless of what difficulty they were spawned at. Master Mode drops have a newly added rarity, . This rarity flashes between orange, yellow and red.
 * Bosses and mini-bosses have a chance of dropping a Relic, a statue resembling the boss.
 * They also have a chance of dropping an item which summons a pet, light pet, or mount that either resembles the boss or is closely themed after it.
 * Additionally, the Eye of Cthulhu has a chance to drop 0x33's Aviators, which – prior to 1.4.0.1 – could only be obtained by defeating Eye of Cthulhu in an Expert world with a Hardcore character.

Trivia

 * Master Mode's descriptive text "Game over man, game over!", is a quote from the 1986 American Sci-fi/Horror film Aliens.
 * The text for a Master Mode world is red. Journey Mode is pink, Classic is white, and Expert is orange.
 * Master Mode was originally intended to be unlocked by beating Expert Mode, but it was later decided that it would be made available to all players.