Hellfire Treads

This is a dead end. Crafting it consumes your Spectre Boots and no recipe takes the Treads any further, so the Lightning Boots line, and Frostspark and Terraspark past that, closes the moment you build them. If you have any intention of finishing that chain, leave the Spectre Boots alone and skip this entirely.

On a short run, or on a character who is never going to chase the full boot line, you lose nothing. You keep the running speed and the flight you already had and gain a flame trail on the ground. The fire is decoration. It does not ignite anything, it will not hurt an enemy standing in it, and it will not hurt you.