HIGH MAGE TABLET
Where I found the High Mage Tablet, I know lots of people want to know and I did as well. FINALLY found it! I hid it just incase someone wants to find it on their own.
Abode of the Earth next to the Dwarven Village, one of the maps after going down a ladder will have a hidden hole in the wall to the left, open up your map to see it! It will be in there!