Is the village near a large body of water? If so, it may be possible to have the non-combatant commoners build several large rafts (shouldn't be too hard, I think) or other floating objects, and when the hoard comes get everyone on the raft and hide out at some place. If all goes well, the kythons may simply move on from your area. If the kythons attack, well...at least they'll be swimming.