Well, to be fair with you I found some earth gem sites just in the same turn Lanka was ordering its troops to attack me, in turn 14
I had bad luck because Lanka was ruled by a veteran player and I think he knew I had a low Dominion. And he had Dominion 6 and a very well blessed troops, with Twist Fate, morale + 2, protection + 2, etc.
I had the possibility to forge the crossbow Just Man's Cross, that fits well to kill demons, but it cost 5 fire gems and without fire gems and without a Dwarden Hammer...
If I had had more time maybe I could have defend better but not in turn 15, it was too soon, wasn't it?