Dresden 5 by Death Masks

started off with the word Insomuch, and the syntax got more opaque from there.
    "I can't make heads or tails of this," I said. "Where's the section about duels?"
    "Fifth paragraph from the end. You want the Cliff's Notes version?"
    I rolled the scroll shut again. "Hit me."
    "It's based on Code Duello," Bob said. "Well, technically it's based on much older rules that eventually inspired the Code Duello, but that's just chickens and eggs. Ortega is the challenger, and you're the challenged."
    "I know that. I get to pick the weapons and the ground, right?"
    "Wrong," Bob said. "You pick the weapons, but he gets to choose the time and location."
    "Damn," I muttered. "I was going to take high noon out in a park somewhere. But I guess I can just say that we'll duel with magic."
    "If it's one of the available choices. It almost always is."
    "Who decides?"
    "The vampires and the Council will pick from a list of neutral emissaries. The emissary decides."
    I nodded. "So if I don't have it as an option I'm screwed, right? I mean, magic, wizard, kind of my bag."
    Bob said. "Yeah, but be careful. It's got to be a weapon that he can use. If you pick one he can't, he can refuse it, and force you to take your second choice."
    "Meaning what?"
    "Meaning that regardless of what happens, if he doesn't want to fight you in magic, he won't have to. Ortega didn't get to be a warlord without thinking things through, Harry. Odds are that he has a good idea what you can do and has planned accordingly. What do you know about him?"
    "Not much. Presumably he's tough."
    Bob's eyelights stared at me for a minute. "Well, Napoleon, I'm sure he'll never overcome that kind of tactical genius."
    I flicked my pencil at the skull in annoyance. It bounced off a nose hole. "Get to the point."
    "The point is that you'd be better off taking something you can predict."
    "I'm better off not fighting to begin with," I said. "Do I need to get a second?"
    "You both do," Bob said. "The seconds will work out the terms of the duel. His should be getting in touch with yours at some point."
    "Uh. I don't have one."
    Bob's skull turned a bit on its shelf and banged its forehead gently into the brick wall a few times. "Then get one, dolt. Obviously."
    I got another pencil and a pad of yellow lined paper and wrote To do across the top, and Ask Michael about duel underneath it. "Okay. And I want you to find out whatever you can about Ortega before dawn."
    "Check," Bob said. "I have your permission to come out?"
    "Not yet. There's more."
    Bob's eyelights rolled. "Of course there's more. My job sucks."
    I got out a jug of distilled water and a can of Coke. I opened the can, took a sip, and said, "That corpse Murphy showed me. Plague curse?"
    "Probably," Bob agreed. "But if it was really that many diseases, it was a big one."
    "How big?"
    "Bigger than that spell the Shadowman was using to tear hearts out a few years ago."
    I whistled. "And he was running it off of thunderstorms and ceremonial rites, too. What would it take to power a curse that strong?"
    "Curses aren't really my thing," Bob hedged. "But a lot. Like maybe tapping into a sorcerous ley line, or a human sacrifice."
    I sipped more Coke, and shook my head. "Someone is playing some serious hardball then."
    Bob mused, "Maybe the Wardens used it to get nasty on a Red Court agent."
    "They wouldn't," I said. "They wouldn't use magic like that. Even if technically it was the diseases that killed the guy, it's too damn close to breaking the First Law."
    "Who else would have that kind of power?" Bob asked me.
    I turned to a fresh page and sketched out a rough version of the tattoo on the corpse. I held it up to show it to Bob. "Someone who didn't like this, maybe."
    "Eye of Thoth," Bob supplied. "That the tattoo on the corpse?"
    "Yeah. Was this guy in someone's secret club?"
    "Maybe. The eye is a pretty popular occult symbol though, so you can't rule out the possibility that he was an independent."
    "Okay," I said. "So who uses