Well... I don't think it's an epic quest, unless they either add in an F2P element of sorts to it, seeing that it happened in F2P too.
I don't believe it's a skill teaser, because how could the ground shaking be that? It was pretty awesome with the sound on too, I think that this is quest related honestly and it's going to be pretty big!
I too think that a new skill is wrong, and an epic quest is right.
haven't we already filled this year's grandmaster quota though
But hey who knows, maybe Andrew just spilled his coffee and raged... anyone thought of that?