This is a Bonehorde Wraith, native to Mophedus, the lower plane of Eos.

The Bonehorde is a rare and unusual cabal of undead. They wander the desolate plains of Mophedus, which lies below the Wildlands. They gather remains of other undead for reasons not fully understood.

Many of the Bonehorde wraiths are the undead incarnations of large humanoids, some that stood over 10 ft. tall.

Nearly all Bonehorde undead originate from Mophedus. However, they are intelligent undead and are capable of tactfully pursuing their victims over time.