Exactly what the amiibo will unlock for Diablo 3 on the Switch is unclear, but based on previous Amiibos in the past, chances are we can expect the Amiibo to unlock additional content, and in the case of the loot goblin, the description says that it will allow players to summon their own portal “to untold riches”.
We can only assume that this will open a level that will let players farm for loot more efficiently, kind of like the secret cow level. There is no mention of how many times players can use this portal, but we expect we should have the details soon enough. The previous datamine had also suggested that there might be more than one Amiibo, and there could also be a Diablo Amiibo and also a “generic” Amiibo (whatever that means).
Those have yet to be announced and it is unclear if they will be, but for now this is the first Amiibo that has been officially revealed and confirmed for Diablo 3. The game has been released for the Nintendo Switch and players will need a Switch Online subscription if they want to play with other players online.