In Markarth, at the end of the murder investigation quest, you get tossed into the mine/prison with the king of the Forsworn, Madanach. My options are to join or kill him. I have no intentions of joining him, but am so far unable to even come close to killing him with a shiv or magic. I've tried everything in my arsenal....bound sword, summoned creatures, etc....and he kills me with two ice spikes within seconds every time.

Any tricks or pointers?

Keep using unrelenting force to knock them down like nine pins .

Have you listened to his story of the forsworn, the braig guy who you're directed to talk to for example.

I'd much rather free a small group of forsworn than do what the corrupt guards/silver-bloods want me to do. In my opinion it's the lesser of two evils, although the forsworn are slightly insane with their satanic rituals etc, the corruption of Markarth's guards is unacceptable and needs to stop.

Edit: little tip, if you wait until the end of the escape, you can fight him on his own (after you get the reward from him) with your gear back. Then you can get the reward from the silver-blood too.

Couldn't care less about the politics...I want to kill the guy!

I used bound sword and stone flesh to kill him. Had to sneak attack him fist though.

turn the difficulty down?

Wait till the end of the escape, you get your gear back and you could try then.

A good trick is to follow along with him and he will lead you and the others out through a small dungeon. Just before the exit he gives you back all of your equipment and a reward.
At that point, if you are fast enough, attack and kill him and the rest of his followers (it should be easy when you have all your stuff). Then when you leave the dungeon the Silver-Blood will welcome you and give you an extra reward. The townsfolk will also have lots of positive responses.

^ Journal entry gets buged if you do this. I use to do this for both the armour and ring, but now I'd rather kill him in the mine. That is unless one of my PCs decides to roll with the Forsworn. I can't confirm, but I think it might bug the mine as well, because it keeps crashing, whenever I try to go in there. Haven't had this problem since killing him where he sat in the mine.

I killed him with a shiv on my assassin chick, but she, of course, had backstab perks and whatnot - I didn't 1-shot him, but I got him down pretty easily.

If you change your mind and decide to escape with him wait until nighttime because fewer NPCs will be on the streets - they can be killed in the fray.

It worked fine for me. The journal updated and cleared ok.

The only trick is that you must attack before any of them exit through the door into the city. So if you're trying it its best to save the game first.

A guard also races through the dungeon behind you and you have to kill them and get out and have your bounty cleared before he catches up with you. So its a bit tricky, but it can be done.