#Do I need to know Luau to add a new item, boss, or code?

For items, Trails, Auras, and redeem codes — no, they're one row in a Config table each, no scripting involved. For a new boss or a new stage hazard, you don't need to write anything from scratch either: the supported way is copying the pattern of the closest existing example and changing the numbers (a model name, two gate names, a distance, a duration) — see Adding a Boss and Adding a Stage Hazard for worked examples. Understanding basic Luau helps if you want to invent an entirely new kind of hazard, but it isn't required for the customization this game is actually designed around.