On the other hand, I've spent about 12 castings of GR on one R'lyan army - mostly Vine Ogres, some Illithids, and about 10 mage/priest commanders. 12 GRs, as many as 4 at one time, plus two armies (including powerful artifacts in one), and I only now have it whittled down to killing strength where I can dispose of the artifacts in order to reforge them.
