You receive this quest from Cainte in Dummonia Village. He lives in the Northern part of the village.
He says only a Druidic wand can kill the Formorian Pirates in because Taran the Thunder God gave them a special armor.
He says you can get the Druidic Wand from the Addanc Islada in the River of the Addancs.
You will also need to get the Addanc Sight Ability to be able to see and talk to Islada.
You will receive the Kill the Pirates quest.
To get the Addanc Sight Ability and the Druidic Wand, refer to the Build a Bridge quest.
Go to the Dummonia Mines.
Make sure you have the Druidic Wand and the Burning Hand Spell.
Enter the Dummonia Mines.
Use the Druidic Wand to kill the Formorian Pirates and use burning to destroy the rocks blocking the path.
Also, refer to the Find the Seeds of Time quest as the Seeds of Time are located in the Dummonia Mines.
When you kill all the Formorian Pirates, return to Cainte in Dummonia Village.
The Kill the Pirates quest will be solved.
You will receive 500 gold, an Iron Axe, and an increase in Fame.