Lavaproof Fishing Hook

It only comes out of crates you pull from lava, which means you need a way to fish in lava before it can do anything for you. In practice that means burning lava critters as bait or borrowing the Hotline rod first. Once it is in an accessory slot the restriction vanishes and any rod with any bait works over lava.

The clean answer is the Golden Fishing Rod. Slotting this next to it gives you one rod for every liquid in the world with a bit more fishing power than the Hotline offers, and you stop swapping gear at the edge of every lava lake.

There is still a reason to keep the Hotline equipped. Running both at once raises how often something bites in lava by a wide margin, and across a long crate farm that beats a small fishing power edge.