don't make an assasin in the sense "all guards know the king"... the assassing really has no chance... he outs himself as soon as he mentions the king ^^.... though he has his kill, a smart town will notice it, wait a bit and just kill him with a delay ^^. If a new player comes and says "Ha! that's the assasin!" then it just scews the game for everyone ^^
baal's 2 faction game is actually close to what I had for a simple game should people had voted for that my round ^^
I had Yoda and Darth Sidious as kings of opposit factions. A mini masson group for both factions that knew the id of their respective king and factioned townies with no info. The only power role was the kings having a night kill.
Of course balance was easy that way ^^. an uneven number of players would have added a third party killer ( like 1 day out of 2 for kills). Win condition was wipe out other faction (including factioned townies). (there were regular days, as most of the population was factioned townies that only knew their side (not who their king was though)).