Currently Online 
Some news from the Nintendo Direct:
"The four Champions Amiibo go on sale on November 10. These figures are based on the four heroes from Link's era: Daruk, Mipha, Urbosa, and Revali, all of whom will play a prominent role in the game's Champions' Ballad DLC. Scanning the figures during the game unlocks a helmet based on that Champion's respective Divine Beast. Nintendo said it will reveal more info about the helmets 'soon.'
The Champions' Ballad is the second DLC expansion for Breath of the Wild, following The Master Trials pack, which released back in June. It is only available as part of the game's $20 season pass. Along with new pieces of gear (one of which will be Link's lobster t-shirt from The Wind Waker), it adds a new dungeon and storyline that reveals much more information about Princess Zelda. The Champions' Ballad is slated to release this holiday season."
Source: https://www.gamespot.com/articles/zelda-breath-of-the-wilds-champions-amiibo-release/1100-6453316/
