Dragons of the world of Ashan.

Angels are also servants of the gods. In reality, such powerful creatures shouldn't be defeated, as the gods would intervene on their behalf. A super-unit should either be a demon or some kind of powerful neutral creature, because if it's connected to higher powers, no sane hero would dare attack it, lest they anger the deity. You might ask, why then do we regularly beat up emerald, black, and lava dragons in the game? Well, these creatures belong to certain races. Each race worships its own deity, so defeating others is a sacred act. For example, the Elves, by killing lava and emerald dragons, are essentially taking revenge on their eternal enemies – the Dwarves and their light-skinned brethren. If you have to kill a Dark Dragon, that's okay. If it's a servant of Malassa, it should join us. If it attacks, it's a heretic. A super-unit should be the strongest and not belong to any race. That is, if it's favored by a deity, it should be the most powerful one, not needing worshippers. For example, Asura or someone even more powerful. And angering Asura is a fate worse than death.