Orctober will begin on the evening of 10/26/18 and last about 2 weeks.
Completing the quest will grant you the Orc Boss' Axe as a reward in addition to a limited edition reward if the quest is played during the event.
The quest will remain in the game after the event is over, however, as long as you start the quest before the event ends you will eligible to obtain the limited edition item - the Orc Boss' head!
Both items can be mounted on the walls in your home.
Note the axe in the trailer is a placeholder. The real axe is still being created, but you can check out the concept art for it below: