The rumors o' yer capabilities seemed overblown, but it appears yer indeed a competent one, aren't ye?
I underestimated ye, <name>. For that, I apologize. Don't tell Thaelin.
The components for the ritual are now prepared. All ye need to do is add the Firelands Slag to the Unstable Magma an' a great bein' from the Firelands will heed our call.
You'll gain control o' it and can eliminate the nearby goblin threat with nigh invincibility.