All Fortnite Season 3 Mythic Weapon locations are spread out around the map.
The introduction of Mythic Weapons vaults has added a new dynamic to the game. Each vault has a keycard, held by one of the CPU bosses at the following locations: The Authority, Catty Corner, and the Fortilla. So let's look at the different bosses and the weapons they guard.
All Fortnite Season 3 Mythic Weapon Locations
Guarded by the character, Jules, players can find the Drum Gun and Glider Gun here. On a side note, there have been multiple posts regarding the ability to unlock this vault without even picking up the key card.
Kit occupies Catty Corner, and here is where users can defeat him to find the Shockwave Charger and the Mythic Charge Rifle. Truly unique weapons can be massively beneficial to a victory royale.
Probably the most useful of the vaults, The Fortilla, guarded by Ocean, boasts the Mythic Burst AR and the Legendary Chug Jug. Two highly important items that can swing a firefight in your direction. Be careful, this is a popular vault amongst players.