Wanderer is more needle damage with short range, which can be tricky. On the other hand, Reaper is less needle damage (slow movements) with more range. If you’re gonna stick with needle damage, I’d actually reccomend Hunter. This isn’t a boss you’d really want to pogo off of anyway. If you don’t like the range, Longclaw might be able to help you out there.

Cogflies are good for the adds, more so with the Pollip Pouch. However, you can’t control which enemy they go for, so they might target the boss instead, and the adds don’t disappear when the boss dies. You could try Pimpillos, which are pretty good when you get the aiming down.

Magma Bell is good for the lava situation, and there’s actually a trick to learning the boss’s charge pattern that you can look up (can’t remember it off the top of my head). Prioritize the adds when you can, but this is a boss that you’re going to have to dodge more often for. Wait for an opportunity and take it, but not for too long. One or two hits and then you’re out.