This one is for solving all of the murder mysteries for Ava's podcast. This will entail all of the missions you can pick up from Ava's podcast mic in her room. You'll want to complete these to get this achievement before starting the next one.
This one is for destroying 50 mysterious Eridium piles. These are the mostly invisible piles of Eridium you'll find hidden around the maps of the game.
A good place to grind this one out is over on the Carnivora map. You'll just drive out (or walk if you're crazy) to this spot on the map where you can find a small shack pictured below to grind this out.
This one is for defeating Hermavorous the Invincible. This could have been a raid boss that required you to have an OP build, or get some friends together, but no it is actually very easy. I just randomly picked up whatever items had higher stats and seemed good, but didn't actually make a build and I had no issues soloing this one.
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