[Truper]

@Viscious Love: to my knowledge, Flames from the Sky and Murdering Winter won't hit stealthed units. If you are certain that they do, please post clarification.

@izaqyos: Counters for stealthed assassins: equip the commanders you especially don't want to be assassinated as well as the assassins are equipped. Recruit cheap commanders, keep them with important forces, let the enemy assassinate these instead.

Stealthy armies are a bit harder. You can have an SC or two randomly moving around your provinces; make the enemy guess what you will be defending from turn to turn. Begin employing the same tactics against him.

I can't give you precise numbers, but the chance of 10 pd + 30 patrolling arches catching a +5 stealth unit I'd describe as "decent". This tends not to help much though - spies will tend to find some other province to incite.

No spells help locate the stealthy.