Spycraft
3 types of spying techniques:
- Human/Fallen as they are plus normal training.
- Human/Fallen as they are plus normal training plus magic support from the Channeler (and/or Heroes/Champions?).
- Magic by the Channelers (and Heroes/Champions?)
Spies are normal units: you take them from the normal population, give them a compulsory training, some optional equipment and s/he is ready to go out there to unmask whichever secrets are to discover. They are not cheap but their cost doesn't increase according to how many you have, and their training cost is higher than usual. Maybe if they are lucky, they may get equipment that can help them in their tasks.
Once out of the school, a spy can stay in any friendly city as hidden police, making sure that no enemy spies enter the city unnoticed (if they are in the same city square) or run more specialiced missions like protecting the warehouse from sabotaging, gaining a bonus to it becuase of the focus in the task.
Another option for them is to go to enemy cities to "explore". They are invisible to any non-spy unit (or hunter/spy/detector Heroe/Champion) so they can travel safely (random monsters appart). Once there, and if the zone is still unknown, it will need some turns before it can be used again. After those turns you get a report of that city square with lesser information and can give more concrete commands to the spy to perform. He could try to destroy the local forge, plant the seeds of rebellion or maybe try to lower the prices of iron of that market in your favor. In any case, since day one there is a chance of the spy being caught based on different things like the number of spies you have in that square of the city, the number of enemy spies trying to catch you, the activity of the spy and the complexity of that activity. Plus any magic involved. Also, they are not limited to cities but they can act also in other structures in the map like mines.
Spies can gain experience and level up as well as get new and (hopefully) improved equipment. With more experience, they can become specialized in one area (saboteur, assassin,...) getting great advantages in those areas and also some extra skills for those roles. A spy could try to assassin an enemy Hero/Champion in the city but if he has become an assassin, he would have more chances of success and being able to try assassination attempts in the wild, for example.
A normal spy should be able to help you in military efforts, economy protection/disruption or social manipulation. Maybe even steals those sweet secrets that your enemy doesn't want to share, including magic.
An enhanced spy is one with the touch of the Channeler (or maybe by one of the Heroes/Champions?). This touch may be a boost of any kind, usually to one area of expertise (maybe stealth to avoid better detectors, maybe more social charm, maybe they gain experience faster,...). They cost the same as a normal spy but require extra time in the sense of the magic used for them (or maybe not but I don't know how "enchanting" people works in Elemental). After that, you get a super spy ready to do whatever you want. Any normal spy could be enhanced by the Channeler at any time, even those who were recruited as normal spies.
As an alternative or as a support method, the Channeler has his own ways of discovering that he wants. Through a variety of spells, the Channeler could mimic some uses of a spy. Low "level" spells would do some lesser work and the most advanced ones would take some (usualyl minimal) essence from the Channeler. I'll give details of the types of spells when Stardock lets us know about how magic works. 
With this 3 ways, one player can spy his enemies in the way he prefers and/or he has to. Hopefully, if a good spying system could be done, it should serve one main purpose: control. Control your enemy by knowing all about him, being able to disrupt supply lines or by simply turning his populacy against him (to the point of being overthrown?).
Then we could talk about racial issues, magic options, types of ops...
I liked Gal Civ II's spy system (the last one specially) but it would be nice to get something more interactive and powerfull/usefull. And unless you have a mode that has combat as optional, or economy as optional, or magic... I don't want to see spies as optional neither. To have mega-events as optionals in Elemental (if there were) would be one thing. To have a whole system as optional... no.
(I'm conscious that I haven't said anything new but I missed to post a wall of text related to the game)