They were created by mistake.
A few Orcs were playing around with wooden wings, like they could fly. Meanwhile, close to them was a hero that was running away from his God, since he used all of his gold on beer again. As the God fired a lightning on the hero, he misses and hits the orcs instead. The orcs started glowing, and the wooden wings turned into real wings.
They are not often, but they are a real trouble. With their teleportation abillity, they are to be found everywhere but Godville, thanks to the number of heroes there.
Like every orc, they are agressive. With the abillity to fly, they make a challenging opponent.
Their strong smell helps them find animals and heroes easier and faster.
Their wings can produce strong wings, so strong it can blow away the heaviest hero.
Their physical strenght helps them throw and drop boulders at heroes.
But, it has some serious downsides as well:
Weight. Due to their weight, they can't fly longer than 5-10 seconds, making them an easier target.
Water. For some reason, skin contact with water makes their skin itchy. The reason is not known yet.
Ugly. If they catch reflection of them, he will be set on fire, and get angry. Useful only if you are fast at running.