But... the cooldown is a lot shorter than the duration. You can easily keep that rune under your feet full time unless the fight is extremely movement driven. On an standing still fight that is a constant, passive, 15% spell damage increase as long as you refresh it once a minute.

There was a blue post a day or so ago saying that the runes are not stackable...again this may all change but that is what they say now

http://wow.joystiq.com/2012/02/17/today-in-wow/

"You can easily keep that rune under your feet full time unless the fight is extremely movement driven."

Here is my prediction: If somehow these runes of power make it live, you are going to have a massive amount of qq, because honestly, standing in a small circle on the floor is seriously the least fun thing I've ever done in ~20 some odd years of playing every kind of mage imaginable in every kind of rpg imaginable.

Movement driven or not, it's just a horrible mechanic. It's one thing if a boss or two have a "stand in this for a buff!" mechanic, like a couple of bosses in ulduar, hodir and the iron council. It's another thing entirely when your entire dps is predicated on standing in a damn small circle on the ground all the time.

I seriously cannot impart on you guys my contempt for this type of a game mechanic. It was so bad in Rift, the devs over there actually got rid of it; wow should take a hint and dump that talent in the dustbin of history.

For PvE and soloing an elite or tough mob, they will be great. You can easily move between the two discs and recast as needed. For PvP it won't be as good, but still at times, when you can get away with standing still for a few seconds, it's not bad.

Actually, in the Forum discussion on MoP talents, I believe Kaivax (Blue) stated in a post that two Runes of Power will not stack. Also, if you cast a third, the first one will disapper.