How would Lo Tae Shao know that Carolinus' crystal ball failed, and then why suggest using Melisande's far sight ability just in time for the sand murks to drive her mad? Because it wasn't him. It was all Ommadon. He interfered with Carolinus' scrying, then sent a fake message from Lo Tae Shao, just to force the green wizard to drive Melisande mad by "accident."
