Soul Blazes and New Spear Use

A soul fire variant of blazes, could shoot soul fire balls that would slow the player down.

Would be extra fast compared to normal blazes

Would drop a soul blaze rod, that could be used to get a short term speed 3-5 effect, or a way to get a boost from a double jump, allowing you to get a speed boost to do more damage with the spear.

They could also spawn in a soul nether fortress with stronger wither skeletons.

Soul Blaze Rods could also be used to get a dash enchantment on boots or leggings, allowing you to get high speed over a short distance, with a long cool-down.