Legends of Ryvalia

Said to be the winged horse which death can be seen riding through scenes of tragic war. 

The true origin of the creature; it was once a normal unicorn before they died out. Back in those ancient days there was a smoke parasite which was ruining humans without any care, so the unicorn stepped in and took the parasite within itself, using pure magic to bind it to the unicorn’s soul and merge them together forevermore. This parasite is what gives the unicorn the black and purple look, the clash of magic causing the damage to the horn, and it also allowed the unicorn to sprout purple smoke wings which carry it from one peaceful location to the next. 

The parasite has been neutralised to a level where it can no longer thrive in another being, but there is still the power to infect for a small length of time – granting the infected with more power. However, it’s just like a virus now, and it will eat away at the host until they perish.