[LDiCesare]

Expanding with assassins works, but it usually means you recruit assassins instead of mages, and it's quite slow.
So it's actually useful if:
-your assassins are mages (e.g. LA Abyssia)
-you are broke and can't afford a mage this turn but can buy an assassin
-you start with an assassin
-you got a free fort where you can't build mages yet but can build assassins
-you found the site that allows you to recruit assassins.
I suppose the assassin mercenary may also be worth buying in order to do this.

Anyone can see other cases where it would be efficient?