Ash Zombie for the soul sand valley

The soul sand valley is great but I think a unique mob for it would be great. My suggestion is to add a new Zombie variant, the ash Zombie.

This mob should spawn on the lower parts of the soul sand valley, at around lava level and should look like the opposite of the drowned, with gray Ash skin and burning (Magma), cracks throughout it. This mob would ideally be able to walk through soul sand at its regular speed and it should inflict fire damage.

I love how difficult the soul sand valley is, though I think this mob would help break up the slightly repetitive cycle of constantly fighting Ghasts and Skeltons.