Master Mode

Master Mode is set at world creation and cannot be changed later, the same as Expert. Everything Expert does still applies: rewritten AIs, better drop rates, Treasure Bags, coin stealing enemies. On top of that, ordinary enemies gain about half again as much health and damage as their Expert versions, landing them near triple their Classic figures, plus another ten percent of knockback resistance. Bosses take a flat fifty percent more damage output and twenty seven and a half percent more health than their Expert values, rounded down, before multiplayer scaling is applied.

One rule change works in your favor and it is a large one. In Classic and Expert, armor cancels only part of the damage attached to a hit. In Master, incoming damage is reduced by your full defense value. That flips how you build. Defense stacking stops being a hedge and becomes the main way you survive, defensive prefixes start competing with damage ones, and armor sets that were merely acceptable elsewhere pay real dividends. It also explains why the opening hours are the worst part of a Master run: before you have armor worth the name, everything hits for triple and you have nothing to subtract.

Master worlds grant an extra accessory slot that is only live while you are standing in one. It stacks with the Demon Heart, so a character who has eaten one and is playing in a Master world has seven accessory slots, more than any other configuration in the game. That slot is a large part of why Master becomes manageable once the opening stretch is behind you.

Coins lose their partial protection. Dying in Master drops every coin you are carrying rather than a fraction of them, and in a world where enemies pocket loose money that is a real loss rather than a walk back. Debuffs inflicted on you also run at two and a half times their normal length, up from double in Expert, so one application of Cursed or Broken Armor covers a longer slice of a boss fight than you would like.

Master drops arrive separately from the Treasure Bag rather than inside it. Every boss always leaves a relic, a golden statue of itself, which is decoration rather than power. Each boss also has a one in four chance of dropping an item that summons a pet, light pet or mount styled after it, and the Eye of Cthulhu always leaves 0x33s Aviators, which used to require an Expert world and a Hardcore character. In multiplayer the pet and mount rolls happen per player for everyone who dealt damage, while the relic drops once for the group.

Master rewards preparation over reaction. Arenas, potion stacks, campfires and heart lanterns are worth building before every fight, because there is no stage of the game where you out heal a mistake. If you have finished a run in Expert and found the bosses readable rather than chaotic, Master is mostly a question of hitting damage thresholds sooner. If you have not, the first three bosses will teach that lesson expensively. It was originally meant to unlock only after beating Expert, and although the gate was dropped before release, the design still assumes you have done it.