Could use some advice on next steps for RF/Fire Trap Inquisitor

POB: https://pastebin.com/vqy7YK3v

So I've gotten most of the easy gear from Pohx's guide, and this thing is sailing through red maps. Clear has improved a lot with Legacy of Fury. I also feel mega tanky with high general max res, split damage, and Supreme Decadence giving me 1k health and 1k ES instantly

I'm not comfortable tackling any endgame bosses with my damage yet though, and the next upgrades from the guide look pretty expensive. Brutal Restraint is still 2.5 ex, Replica Soul Tether is dropping at least but it's still 4 ex, and I don't think I'm ready to go Aegis (7 ex?) with my gear level.

I currently have about 10 ex left, although I can make decent currency when I'm actually focusing on it.

I'm trying to figure out what's the best bang for my buck at this point. Would it be a cluster jewel?

Also what's a good way to get Onslaught so I can replace my Death's Rush? An Abyss gem? If I can replace Death's Rush with an Amethyst I think I open up a lot of options.