If you have Samsung Galaxy S6, you get 3 classic packs and a card back after logging in via this device, if not, you can emulate it on for example PC and get it anyway if you want to go through a bit of an hassle.
I will repaste and fix the guide posted on reddit..
Step 1. Download Genymotion
https://www.genymotion.comStep 2. Install Genymotion and add a Google Nexus 7 - 4.3
Step 2.a. Click Settings icon next to Google Nexus device and change CPUs to "2" and RAM to "2048"
Step 3. Start the emulator
Step 4. Download
this file and drag it into the emulator then restart the emulator
Step 5. Download
this file and drag it into the emulator then restart the emulator
Step 6. Open the google play store, add an account, and download
Hearthstone and
Build Prop EditorStep 7. Open
Build Prop Editor and change the ro.product.brand class to "samsung" and the ro.product.device to "SM-G920F" then add (with a + icon on top) a new string "ro.product.model" with "SM-G920F" class
Step 8. Restart Your Emulator
Step 9. Open
Hearthstone Change region to EU, Sign in and enjoy
I just got my second Ancient of War thanks to that cheat xd