I believe it is indeed not working as intended.As far as I know the only thing to make it work is a DKs Icy touch.As for FFB spec,both FFB specs(one with LB,one with CS) they both work as intended,no bugs there and the DPS you gonna pull as FFB mage is quite big(you're either first or 2nd on recount if you know what you're doing on every fight).
Bump for this. If someone would make this clear once again. Had a talk about this and wanted to know for sure again. And with icy touch doesnt the dk need the talent for the slow? And this is for Wotlk ofc.
And I've been rolling FFB for a while now but thinking about switching back to TTW.