Link your battle.net account by:
Go to https://battlefy.com/settings and choose the Connections Tab
Clicking on "Connect" will take you to the battle.net authentication page.
Note: if you are already logged in to battle.net on your default browser, this will automatically connect that account. If you have multiple battle.net accounts and wish to connect a different account, you must first log out of battle.net on your browser to be prompted to log in during this connection.
Once you log in you're all set!
If you need to unlink your Battle.net account from your Battlefy account, follow the same instructions but press the "Disconnect Battle.net" button.
The Battle.net connection is necessary to participate in Hearthstone and Overwatch Tournaments.