The Mad Mage - Artemis?

Powerful magic user. Turns himself into a stag. Lives on Mount Baratok.
Lost his memory.
Casts some sort of mind protection magic on himself to stop people getting in.
Eva Prophecy - Mage with broken mind - Esper
700 years old? Creator of Buster?
Name - Artemis He was the architect of Castle Ravenloft. Regretted it later.