The explosion that shook the castle while we were discussing the war was in fact a test by Moody. To test the wards if they could withstand a significant amount of force. The Auror’s he had with him were in complete shock at the power he used just for the test, added by the fact that the wards stood strong afterwards. Avalon had possibly the strongest ward system in the Material plane; very few spells or projectiles could make it through the shield being powered by the very leylines that course through the isles. 