1. let one of your cities become a festering cesspool of disease. evacuate any important characters from the city.
2. while you're waiting for the black plague to strike, build a bunch of spies.
3. when disease strikes move your spies onto a boat.
4. sail the boat to an enemy city, preferably one with a faction heir, king or other important character.
5. send a few spies into the city. you may want to keep some on the boat to recirculate the disease on board. try to keep the disease going as long as you can.
6. if the target city ever rids itself of the plague, just send another infected agent in to spread the love.
this works great because.
a) spies incite rioting.
b) disease incites rioting.
c) rioting may destroy happiness buildings, which makes more rioting.
d) disease may eventually claim an important character in the city.
i managed to destroy most of the buildings in paris and wipe out half their soldiers by keeping the city sick for a few turns. they lose about 100 troops per turn.
of course i haven't done a full analysis on the negatives of this plan, haha... but i thought it was a fun thing to do when i realized my spies had got the plague.
if you guys happen to try it post your results here. i want to know if you can kill a king this way.