Hello,
i feel like it isn't really being mentioned anywhere, but in ruthless, since you most likely won't have a 6 link, or good ways of scaling damage, the easiest way to scale damage is to just use many different skills.
The premise here is that on non bosses you just fire trap and maybe curse a rare here or there, and on bosses where you struggle, you are unloading your whole kit.
Here is the POB: https://pastebin.com/LmjmdEM1
Lvl 98 with 2-3 mod gear, no 5 link, the mods affixes and bases are not tier 1, usually tier 2-4 (except the weapon). Should be overcapped for curses, 600k boss dps, and is reasonably tanky to not die to do all the content except ubers.
I don't think ubers are doable for anyone but 1-2 players, since you would need way too much time to get the gear, so this is a good build to basically farm the endgame without ubers.