Geeze, you have some sadistic choices in the game. I was hoping to smack the owl with a crowbar or dagger, not murder some innocent tree unnecessarily in the process!
Anyway, I have one last spell I need- "Windstorm." Prospero as usual is being deliberately vague, mumbling something abut "Angel Wings" in the "Real" realm. I already gave him an owl wing for something else, and I can't interact with the angel statue in the town cemetery.
Sigh.... almost completed my spell book though!