Thanatos

Fly to the right till you get to a castle, then land and walk up to the castle gate. Use flame from close range to burn down gate. If you run out of flame go back and find a witch tied between two stakes and eat her (just walk up to her slowly). This will refill your energy shown by glass (on the bottom right of the screen). In the first castle land near the girl (who will coloured green, and will be waving with both arms), and allow her to climb onto your neck (ie: just land nearby and wait). Fly onto the next castle. When you find the book of spells, land and let the girl collect them. Fly to the last castle where you will find the cauldron in which the girl can cast her spell. Land nearby.