LASO

 Mythic Difficulty is the fan-created difficulty in Halo 3 and Halo: Reach, obtainable by activating all Skulls in the Pre-game Lobby and setting the dificulty to Legendary. Mythic is sometimes considered different to another fan-made and Bungie approved difficulty LASO (Legendary-All-Skulls-On), which has been featured in Reach's challenges, the supposed difference is that to some players Mythic Must be completed without dying, at all, and on solo.