All we can hope to do is slow it down long enough to get into position to extract the shards from Luther. Unfortunately, I can offer little in the way of resistance against such a device, but perhaps the spellcasters can create walls or summon powerful creatures to aid in subduing it.
And I agree with Kerkly and Benlin. If someone can send Asinjin, he may be able to Greater Teleport in and equip us with the scarab.