not necessarily, I think the formula goes about x MP for the teleportation spell itself plus y MP per km/mile, so for humans with only a few hundred MP, they have to sacrifice all of it and dying in the process, even with a single teleportation to the next land, a strong demon like Gaarv with ten thousands of MP can do himself even twice with more than one people, no problem at all - so if the demon king has even more MP, he maybe can send her back with his powers alone