Mythic
From Halopedia, the Halo wiki
Mythic, often shortened as LASO for "Legendary with all Skulls On", is a "fan-made" difficulty for the Halo series.
Overview
In order to play on this difficulty, the game needs to be set to Legendary and all the Skulls activated. Mythic is possible in Halo 2, Halo 3, Halo 3: ODST, Halo: Reach and Halo: Combat Evolved Anniversary. When played solo, its shortened name is "SLASO"[1]. Halo: Reach weekly challenges often include a challenge in which the player needs to complete a certain campaign level. Although it can be beaten, the game stats will still read "Legendary" since Mythic does not exist in the game's code. For the same reason, the difficulty does not have an icon like the official ones.
Trivia
Players can exploit the "Save and Quit" option in the pause menu whenever the player dies. When the player resume gameplay from the Campaign lobby, they will start from the previous checkpoint and may continue to the end of the level. Doing so will still reward the player the weekly LASO challenge.
