Genshin Impact is no doubt heavily inspired by Zelda: Breath of the Wild, as it uses a gorgeous art style to really immerse you into the game. Though it is about questing and slaying enemies, it's very hard not to get lost in the beauty of the nature surrounding you. There are tons of quests that will take you all over the world, so take your time and soak it all in! On occasion, a certain quest will unlock that is known as a Weekly Boss, and by completing the challenge called Razor's Act 1 story quest, the Boss Andrius will emerge.
To unlock Razor's questline, The Meaning of Lupical, it requires you to be Adventure Rank 21, and have completed a few story acts. Act III of the Prologue Archon Quest and Act 1 of Amber's Story Quest must be finished before Razors will unlock. After these and Act 1 of Razor's quest are done, it will lead you to challenge Andrius as a weekly boss.
Andrius is actually known as Boreas, is one of the Four Winds protecting Mondstadt. His official title is Wolf of the North, and when its kin, the wolves, are threatened, the noble soul will take the form of a wolf to defend its family.
Weekly bosses are much more difficult to defeat than elite bosses; however, it's a very risk-reward scenario! If you manage to defeat a weekly boss, the rewards are fantastic, but only if you spend 60 Original Resin to do so, as a Trounce Blossom emerges. Trounce Blossoms are like Ley Line Blossoms when you complete a Blossom of Revelation or Wealth. You can, however, choose not to spend the 60 Original Resin on the reward.
At this present time, there are two weekly bosses, Andrius and Dvalin (Stormterror), and don't worry if you've killed it before, as these bosses respawn every Monday, so make sure you have your Original Resin filled up to reap the awesome rewards!
If you are having trouble with this boss fight, as weekly bosses are the hardest bosses in the game at the moment, you can watch this video for an in-depth boss guide on how to defeat Andrius.