Wonderfully Inventive!
What a fun story--very cute how you wiped out the Phoenix threat for your team, but even more wonderful how you used the Snarry competition to spark your imagination for such a creative story. I loved the period setting, and the way the relationship between Prospero, Harry and Severus developed. I loved how Prospero expressed emotions that Harry was unable to express at first--the way he was physically drawn to Severus and able to communicate with him from the start and the way that developed into human love.
I also liked the way you re-imagined magic--it didn't seem about waving a wand and spells as much as it was rituals and transfiguration--more complex magic, less everyday magic. I don't know if it was intentional, but I really liked the subtle change it made to the magical world we're used to with HP.
I was curious about exactly what happened with Draco and Harry while they were away--I was very curious about their adventure. A little worried that Draco might try to entice Harry away, I must admit, but it seemed like a fun trip, and I wished I'd seen more of it.
Mostly, I think that this was such a rich world that you could create a novel-sized fanfic out of it, so all of the hints you gave of things happening off-stage or things merely alluded to, made me want more.