Context: I was constructing Terraspark boots, gathered all ingredients I needed except for lava charm and water walking boots. I took so long time to find them that I've found boots from seaside (hardmode) crate and decided to look for magma stone so that I could shimmer it into lava charm. Why? cuz before hellbat hunt I fished 11 hellstone crates and got none lava charm.... 5% chance, yeah, but still...

anyway, Terraspark boots can be crafted in pre-hardmode, but I got them only in Hardmode cuz of 2 ingredients with which I had the least luck... But boots are mine now, finally))

P.S.: I am totally aware of this RNG behaviour in Terraria, just sharing how it turned out for me