The Tormented

In The Nether/Overworld black spirits can be seen flying about the world which all noticeably have Wither Skulls as heads. in the Nether there is a small chance that after killing a wither skeleton a tormented will spawn straight after deciding to avenge their body instead of being at peace or perhaps there could be a chance that a wither skeleton that spawns glows inside it’s head which would signify to the player that a tormented would spawn after death. They could also have a very high spawn chance in the soul sand valley suggesting that that is their resting place and that the player is intruding it.