Quote Originally Posted by Seamus Fermanagh
I've had one Brutii diplomat whose career was ended abruptly by an Egyptian assassin. This is, however, the only instance in dozens of hours of play. Assassins are late-game creatures for me -- its hard to justify the expense until you've got A) good income and B) someone who can with traits etc. build them for half cost or so (Diplomats for 90d!).
Recruitment costs are a one time fee. The real costs in SP campaigns are their upkeep, recruitment costs are marginal.

I usually have 4-5 assasins at any given time, have them kill low level diplomats and if I encounter them, spies and other assasins- generally I only accept with a >80% chance of succes. If necessary I even target captains even though that won't really hurt the enemy. Anything that can pump up their experience.

After a while, they can even take on low-quality family members. That's when they become really useful.