A pair of boots, that do similar to the Frost Walker enchant, but to lava instead, either turning the lava into obsidian or cobblestone

Turns lava into magma blocks perhaps? Also, Hellfire Boots 

Gplayer and I were JUST talking about this idea yesterday too.

I could imagine this having Fire Resistance V or something and making it Magma Blocks (so you take less damage cause they deal fire damage) without being OP since no one uses anything but normal Prot anyway xD

Alternatively make it turn into basalt and leave it with normal enchants, to mirror the idea of ~Ice + Lava = Basalt~

But regardless, 100% love and endorse this idea :)

Also, Hellion Boots