Does the assassin kill in secret?
Nope. His one and only kill is a public Ninja like kill, that slays his target and himself.
(I flip out and kill X, or in this game it would be more like "I draw my blade and charge X, hoping he's the Duke, but am slain by his guards at the same time my blade finds his neck")
Why does the Duke not start out knowing who his guards are?
Well, because then the only person he wouldn't know is the assassin. The game would be pretty hard for him, then!
When you say his kill is in retaliation to a lynching, does that mean he can avoid being lynched by just killing randomly?
Yes. If the assassin gets lynched, he can (and should) use his kill to try and kill the Duke.
Questions: is the Assassin's flipping out and killing a suicide mission like the Ninja? i.e. Does he die as soon as he kills? Or does he then need to be lynched, giving him basically two kills (one proactive, one reactive)? With no night phase, does the Assassin kill only through the lynch, or do they paint their target prior to the lynching?
The Assassin kill is exactly like how the Ninja works. He declares it in thread, and both he and his target die.
He does not need to be lynched first in order to do this if he is sure of his target or whatever. Their target is only declares at the time of them flipping.
It should probably be illegal to say "I flip out and kill X" if you're not the Assassin.
Er. Good point! Yeah, unless you're the assassin, you can't "fake" doing this in order to flush out the real one :3
Alright let me give you an example game, just so you get an idea in your head of how this should go:
PlayersBob
Jane
Dick
Kitty
Puppy
Bob is The Duke. Kitty is the Assassin.
On Day 1, the usual last person to post bs is done, and they end up lynching Jane. She is, of course, a guard.
Day 2 follows, and Puppy accuses Dick of being a prick. They lynch Dick, who is again another Guard.
Now it's lynch the Assassin or lose, because if another guard is lynched, then it will be only The Assassin and the Duke, and obviously the Assassin will know who the Duke is then. Bob, Puppy, and Kitty remain in the game. You lynch Kitty, but she flips out in response, and, being an astute wolf player, notices that nobody ever voted for
Bob the entire game.
Hmmm. Since all the guards know who the Duke is, it might make sense that Bob is indeed the Duke they were trying to protect. She flips out (despite being lynched by the other two) and kills him, winning the game.