This is Jack - a guy that met Satan and tricked him into promising to never take his soul He wasn't good enough for paradise either, so when he died he ended up in purgatory Death has now brought him back to life to deal with Satan's Halloween Shenanigans, in exchange for a solution to his Eternal Torment
You can no longer jump from a slide, which caused a bug. You can no longer kill Hell Knights (and large enemies) with Slide.