As for taking the Nagas, I recently took them (in a game with bRitvo4kA) on the 2nd Naga Bank on 3 with a ground stack, a scout hero (swamp dweller), and saved all the Gremlins and all the Nagas. I wouldn't say it was an easy fight, but no harder than for other castles. IMHO of course, but I tested it. ;)