Your writing truly has potential. You manage to be extremely discriptive without burning your readers with too many adjectives and adverbs. The sentence structures used throughout (length, composition, word placement) help the readers to pick up the emotional wave lenght on which you have placed your interpretation of the character.
If I may be so bold as to offer some little constructive criticism? Here and there I believe your word choice could possibly have been better. Starting three consecutive sentences with the same word is not often a good idea, even if it is the name of the character. Throughout, there were only one or two other words that niggled a bit.
But overall, I truly believe you did a very good job of displaying your interpretation of the character "Merlin" whilst still staying true to how he was originally shown to the viewers. And you did this all in a very short piece of writing, which is quite impressive.
You seem to have a natural feel for the flow of story telling, for putting words on paper and making the reader see what is happening in their mind's eye. I jave read quite a few fanfics, but it is not often that I have found an author who is able to do that without boring their readers within the forst three sentences.
Truly, well done. I hope to see more of your work in future.

Good job on your first fic. Keep going!
One or two suggestions: spell check, okay? Especially the title then more people will want to read. Also, ending the story like you did makes it feel like you started going into another part of the story and quit. It's not a clean tie up.
Things I really liked: it's original! In all the fics I've read, I've never seen anyone explore this moment when Merlin's magic reaches its potential. Nice!
Another thing I love is your second sentence. It is beautiful.
Thanks for sharing!

You painted a very pretty picture. I think it would have been better to end it one sentence earlier. But I like the imagination in this.

Hope you guys like my take on events