I had this interesting conversation with someone recently about fantasy. It's someone I need (and want) to get along with, but he said the one thing you can't tell a fantasy writer:
"Fantasy is easy. You can just use magic to solve everything."
I hesitated between growling, laughing or crying, went with a simple shake of the head and I did not even comment the subject. That's how badly I needed his approval! Only, he brought the topic up again, and since by then I had his approval (m'hahaha), I debated his point.
Magic isn't a Deus Ex. If your magic is a Deus Ex, you're doing something terribly wrong.
The fun thing with magic is that you can do anything with it! If you have a superb, eccentric idea that involves magic, you can grab it and run with it. It's the ultimate freedom of fantasy.
But as a French theatre director once said: "Freedom is the liberty to choose your limits."
No matter what your magic is, you must establish the laws that rules it early on (don't infodump it, though. For the love of all that is holy, don't infodump it). It cannot be unlimited. There must be a cost to the magic, or a limit that is impossible to break. With magic, you are bringing a new set of natural laws, just like physics, and you must abide by them.
Don't break your rules. Those who do are the reason we have this reputation of Magical Deus Ex. Be smart, and enjoy your high magic. When you do it right, it's a boatload of fun!