In Heroes of Might and Magic III, if you don't use overpowered creatures like Azure Dragons and other mutant dragons, this is the strongest monster. Hobo listed the monster stats but forgot to calculate the amusing ability of this creature, which reduces its target's defense by 80%. So, in a 1v1 fight, it will defeat everyone. But if you start considering that the dragon is immune to magic, the angel revives, the titan shoots, etc., then it depends on personal preference :-)
P.S. In tournaments, the Conflux Castle was quickly banned, most likely because of the Phoenixes 8)).