With magic now being a pool again, this item gets a little bit better, though not as good as when it worked for both dispell and casting dice. However, with magic the way it is, can you see there being a case where you would have magic dice left over to transfer into your dispell pool.
If you don't have a Slann then I can see the item being used. Otherwise you probably won't have any dice left over after casting with a Slann.
I have a sole skink priest (lvl2) leaving me with either handful of dice left or going overkill on iceshard blizzard. On the other hand mages aren't all too common around here anymore. Possibly my chaos friend, but that's a given. Cheers!