Sciron - Act 5 Side Quest
Start Location: City of Corinth
Quest Location: Scironean Rocks
Objective: Defeat Sciron then return to Demokrites
The Sciron quest begins by speaking with Demokrites who is found in the City of Corinth, the first town of Act 5. This quest can't be picked up until after you complete the Troubles of a New Age Main Quest. For this quest you will need to travel northeast of town until you reach an area called Scironean Rocks. You will find Sciron a little bit off the primary path to the north, he'll be surrounded by tons of bandit enemies in a large encampment.
All in all the fight with Sciron is a pretty easy one - at 60% health he will retreat into the back of his bandit camp and agro all of the bandits throughout the camp if you follow him. For this part you can stand at the mouth of the bandit camp and he'll eventually return to you and keep fighting but you'll need to go into the Bandit Camp anyway for the Majestic Chests.
With Sciron dead return to Demokrites and talk with him to complete the quest.