Hey, I was going to resurrect this when the time was right. No matter, the discussion is good.
The battle one is very important, and I'd love to see it ingame.
The way I see assassins working is this: An enemy faction sends an assassin, or groups of assassins (depending on player level), after the player's party. Their speed would be very high compared to the player, so they would catch the player's party. Then, we jump to a battle scene with the player and his/her heroes, vs. the assassins. It might become far too easy to spam assassins then, though. Maybe a castle only has a few possible assassins, and they regenerate slowly?
@ Amman--I'm not quite sure what you mean. You're saying that the player has to capture the assassin first, and then the battle begins? Why wouldn't people just not capture them?