[Xietor]

There are no allies, so if you cast an assassination spell at a castle under siege, say Earth Attack, it is random who your Earth Elemental will attack.

If you are the force laying siege to the castle, your assassination spell will hit the other player's mage inside the castle.

That clearly applies to spells like Earth Attack and Disease Demon that hit enemy commanders inside castles, and also to spells like seeking arrow and fire from afar that hit only enemy forces and also target enemies located inside castles.

Manifestation can target your own casting mage. And Leprosy will target your forces if they are in a province as well as enemy forces. Leprosy of course is not an assassination spell.

Hope that helps some.