Consequences of Magic

[Zappo]

Which brings me to a potential Hook. If we can summon creatures to our world to fight for us, why can't it be done the other way. Immagine the look on your players face when you tell him he has been summoned to another world to fight on behalf of what he would consider an outsider. Now he is the outsider!

There's a 2E Planescape short adventure which has exactly this theme. Except that the summon there is more like what in 3E is a calling.