minimum level 55, but you'll hurt a lot. i'd say 59 or 60+, because you'll have a better chance of resisting some of the AEs and subject your raid to ...
I want to call attention back to a post I made waaaaay back when I first finished my set of Focus items. I have gone through it and altered it to fit the current changes in the game and I want to point out that if you are a 45+ Mage it is absolutely essential that you get the Torch (for the Rak'Ashi