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
So I created the Hell Knight and created some behavior for him. I also added patrolling that can be enabled for units and I added shields to skeleton warriors to make them a bit less vulnerable.