Expert Mode

Expert Mode is chosen at world creation and locked in from that moment. The headline is that most enemies carry double health, hit for roughly double damage, shrug off ten percent more knockback and drop two and a half times the coins. The raw numbers are the least interesting part. Attack patterns change, bosses gain phases, and several ordinary enemies pick up moves they simply do not have in a Classic world. Everything below also applies in Master Mode, and every Expert-only item can be obtained there.

Two changes pull your build in opposite directions. Defense is fifty percent more effective than it is in Classic, so every point of armor buys more than it used to. Passive health regeneration is halved unless you have the Well Fed buff, and only recovers to three quarters of normal with a Shiny Stone equipped. Lifesteal takes a smaller cut too, so Vampire Knives and Spectre healing return less than their listed numbers imply. Food stops being optional, defensive prefixes become worth real money, and you can no longer heal through mistakes the way a Classic world lets you.

These are the changes most likely to kill you before you notice they happened.

• Jellyfish gain a charging attack during which they take no damage at all, and swinging a melee weapon, whip or tool into one mid charge hurts you instead.
• Some Zombies carry a Zombie Arm, which reaches past where you expect the hitbox to stop and hits harder when it lands.
• Spiked Slimes fire a burst of up to six spikes around themselves, so standing beside one is no longer safe.
• Skeletons throw bones, which turns a melee enemy into a ranged one in any corridor you cannot leave quickly.
• Lava Slimes leave a block of lava behind when killed, and it will happily burn the loot you were walking over to collect.
• Black Recluses and Jungle Creepers spit something that pins you in place for a moment, which is usually long enough for whatever else is in the room.
• Granite Elementals shield themselves once below half health, so burst damage beats chip damage against them.
• Bats and Duke Fishron can inflict Feral Bite, which applies several unpleasant effects in one hit.

Coins on the ground are no longer safely yours. Most enemies pick up loose money by walking over it, make a sound when they do, then sparkle in the color of the best coin they carry. If one escapes with a meaningful amount, the game records where it went, marks the spot on your minimap and respawns it holding the money when you return. Kill the sparkling one first, before it wanders into a biome where it cannot legally come back.

Each boss has its own multiplier applied to its Classic health, and they vary widely: Skeletron doubles, while Plantera only gains forty percent. Multiplayer stacks on top. The second player adds thirty five percent, and every player after that adds a third of whatever gap remains between the current bonus and the next full step, so each extra body matters less than the one before it. At ten players or more the total is rescaled again through a separate formula. Health is fixed at the moment the boss spawns, so anyone who joins mid fight is free damage.

Every boss except the Lunatic Cultist, the Dark Mage and the Ogre drops a Treasure Bag when it dies. The bag holds a larger helping of the usual drops plus one item that exists only in Expert worlds, and in multiplayer everyone who dealt damage gets their own. Bags can be carried into a Classic world and opened there, and the contents work fine, with the Demon Heart as the sole exception since its extra slot only activates in Expert or Master. Hardmode bags also carry a one in sixteen chance of a full developer set, Queen Slime excluded.

• Debuffs inflicted on you last twice as long, which moves an Ankh Shield up your priority list and makes Cursed and Broken Armor genuinely dangerous.
• Enemies can spawn near town NPCs. They still cannot spawn in front of placed background walls, so walling the interior of your town is the fix.
• Touching water or Shimmer inside a Snow biome inflicts Chilled for as long as you stay in and for five seconds after you climb out.
• Respawning takes fifteen seconds rather than ten, and thirty rather than twenty if you die within 250 tiles of a boss in multiplayer.
• Pots and fishing quest rewards roll better, the Traveling Merchant has a coin flip chance of an extra item in stock, and enemy banners give stronger bonuses when hung.
• Pumpkin and Frost Moon waves advance at double speed per kill, which puts the late waves of both events within reach far earlier than their Classic versions.