[Taqwus]

It might be useful to instantly seize the artifact on which another nation happens to be relying -- for instance, if they're using Tempest for the storm + thunderstrikes, or running around with a sacred army bearing the Ark. Might be especially nice if you're nowhere near capable of building the artifact on your own. Or stranding the army that's using the Flying Ship...

Haven't really played around with seeing whether you can seize elemental/demonic royalty this way, or whether it only clones them. Or, say, the Tlaloques.

There are certain nice national summons that might be of interest -- if you can summon the Seraph (the angelic one, not the Caelian -- this would require summoning via monster number, something I haven't personally verified), he's a nasty SC that's normally restricted. A Mandaha might also be great fun for the Ashen Empire, considering the free darkness -- even if the Mandaha were not restricted to Lanka, the Ashen Empire is hardly the best nation for blood hunting.