to avoid Nomad's 750 hit, you need to wait untill he lays down those red mines around you. there is an opening directly south of you in the ring of mines, exit out of the mines through there, and go east and north around them (carefull not to step on one, they deal up to 400 damage and drain your run), assuming you're ranging, continue ranging him untill he stops and says "You cannot escape my wrath" and starts charging. Now, when he's doing this, you run behind a piller so you are on the south east side of it, when he fires his attack, it will uselessly hit the pillar. Take the time you;re behind the piller to drop any vials you have so you can take more from your BoB
NOTE: if you see NOmad say "Face me you coward!" You better do it, or he'll go back to his throne and heal to full HP.\
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I've been questing myself today, I'm ganna try to get to at least While Guthix Sleeps so I can fight tormented demons. During the "Dealing With Scarabas" quest, I actually died and had about 50m worth of stuff under my grave. Luckily I made it back to get my items, and was more prepared my second time going through. My next quest will be Great Brain Robbery.