Legendary Mode

Legendary Mode is the aftermath of creating a Master Mode for the worthy world. Due the for the worthy seed's effect of upgrading the difficulty, Master Mode becomes Legendary Mode. Legendary Mode is  harder than Master Mode, taking the place of being the hardest difficulty. Unfortunately, Legendary Mode is not available in the world creation menu, and is only an easter egg the developers put in the game.

Unlike the others, Legendary Mode does not have it's own exclusive drops. But Master Mode and Expert Mode drops are available in Legendary Mode.

Trivia

 * In the world selection menu, Legendary Mode's text color is lime.
 * When 1.4.4 was in development, Terraria's development team considered adding a feature to the for the worthy seed. That feature would upgrade the difficulty chosen upon world creation to the difficulty harder then that. But they needed something to upgrade Master Mode from. And so Legendary Mode was created.
 * Legendary Mode doesn't have a description like for example, Master Mode's "Game over man, game over!" because it isn't available to the world creation menu.