Towards the end of a game, agents play a more and more important role. If you are a non-agent nation, you can counteract the one sided-ness of a game by producing some super agents of your own after turn 20 in record time.
This ploy is best served by non-agent nations but can work for anyone.
By turn 20, if you have been playing the Dwarves or Arthedain or the Fire King for example, agents won't have been top of your agenda. However, it now would be nice to start making some agents with a bit of punch.
Here's what to do...
Form an emissary company. Your emmys at this point should be typically 60+.
Ask a team-mate to form an emissary company with ranks 60+.
In each company put in the agent you want to improve.
Arrange with your team-mate for the two companies to meet.
When the two companies are in the same location, the emissaries try to double each other, the agents try the counter espionage order. This order is a Average difficulty so it shouldn't be too difficult to achieve with a 40 agent.
What happens is every emissary doubles one of the 'enemy' emissaries. These emmys get a skill rise to improve their ratings. Approx 4-7 points of skill.
The agents get 1-5 points PER CONVERSION. If there were 5 emmys in each company that's possibly 25 agent points! This many points are highly unlikely but you should get 12-18 points of skill increase per turn. Three or four turns of this and you can have a great agent.
The only downside is the agent and emissaries are not being 'useful' for those turns. They could be better employed improving pop centres or influencing away enemy pop centres. Still, its a good idea!!