If a creature is transformed into another creature (say, a human into a dog), then that creature will become more and more accustomed to the new form until a point is reached where reversing the spell is impossible. A second transformation is possible, but the creature will have to go through the whole process again.
An ancient, psuedo-immortal race has been manipulating something important (politics, religion, economics, etc.) for centuries. Hardly anyone is aware of them, let alone their goals.
Jemas Lorne, the most celebrated poet of the age, was found dead, clutching a fragment of verse torn from his journal. The tantalizing fragment spoke of wealth:
Golden sands, empty and cold,
Treasure's crypt, forgotten gold.
Under stone, ancestor's doom,
Noble's prize, troubadour's tomb.
Rumours claim that the poet's father, an eccentric nobleman, had hidden much of his wealth before his death. Perhaps the missing journal has more clues?