Is it in any way possible for a core engineer (with rifle) to kill Subject 7 in the Queen's Gauntlet without killing any oozes (for the Blobs, Schmobs achievement)? I'm trying different methods but there is always AoE damage that gets at least one of the oozes...
If you're absolutely stuck with just core engineer and rifle, try equipping Elixir Gun and just 111-ing it down with Tranquilizer Dart. It's not the strongest thing around, but it's one of the few autoattacks engie has that doesn't pierce, bounce, or explode. Make sure you don't have any traits like Aim-Assisted Rocket that trigger yet more AoEs.
I also have some hero points invested in Holo, but didn't really dip into it yet. However with most skills I'm using he regenerates HP too fast and the oozes do too much damage. I think I need to postpone this achievement until later when I have better equip or another character which is more suited for that task (I read that Necro is quite good)
Yeah, I think back when I did those acheevos it ended up being a mix of necro, mesmer, and maybe guardian, even though I'd rather play engie. Can count on it coming back next year if you don't clear it all this time around, though.
Took me roughly 10 seconds on my Soulbeast with Longbow. I know, this does not help your cause, but I like that GW2 professions have still (after many balance patches) unique strengths and weaknesses and that GW2 is still (even after EoD jade bots) very alt-friendly.