Using an amiibo in Age of Calamity is easy to do. When you first open the game and load into the main menu, you will see an amiibo option. This will prompt you to scan amiibo in Hyrule Warriors: Age of Calamity to get various rewards. The game will hand out a variety of rewards from this, including rare weapons and more. This is a good way to get a nice cache of supplies and weapons to use for the various side activities.
How to scan amiibo in Hyrule Warriors
Simply load into the game and choose the amiibo option on the main menu. The game will prompt you to place your amiibo against the scan point—on the right-hand JoyCon by default—which will then give you your reward.
I’ve tested it with both genuine Breath of the Wild amiibo and cloned NFC cards of ACNH villagers, both appear to work. So if you’re running those cheap NFC 215 cards for ANCH, you’re in luck. And from what I could find, you can scan an amiibo more than once, provided you only scan it once a day. You can scan a total of five amiibo in Hyrule Warriors: Age of Calamity per day. There are some restrictions though.
Be sure to save your game after you redeem and amiibo. If you just shut down the game without saving, the reward will not be saved.
For one thing, you can only scan one character per day. That means if you have two Link amiibos, you can only scan one version per day—the same is true with other characters. For example, if you have a Super Smash Bros. version of Mario and another version, you won’t be able to redeem that second one.
The bad news is that there’s no way to predict the rewards you get. There appears to be a random loot table that the game generates for each amiibo scanned. The rewards are completely randomized as a result, and it’s impossible to say what amiibo will give each day. This is a change from previous franchise games, as both Hyrule Warriors and The Legend of Zelda: Breath of the Wild rewarded set items for amiibo.