*Taken from xboxachivements.com as I have not earned it yet*
This occurs in the Lord of the Hunt DLC.
This will most likely be one of the last achievements you unlock during your playthrough as it requires players to complete all the main story missions. In total, there are five Warchiefs that must be eliminated in Nurn. You can check their details below for a general description of what’s required during each of their missions.
Call of the Caragath – Stealth kill the Warchief’s 5 supporters while mounted on a Caragath to lure out the Beast Tamer out without raising an alarm
No Rest For the Wretched – Hit 20 Archers with the Wretched Graug’s Projectile Vomit to draw out Beast Butcher
Blasted Uruks! – Chase down and kill 10 Uruk couriers in order to draw out the Smuggler
Stronghold Uprising – Bait a horde of 3 Ghuls inside the Stronghold to cause chaos, thus luring out the Graug Rider
Homewrecker – Hunt down the final Warchief and put an end to the Beast Master threat in Nurn
Overall, these story missions aren’t too complicated so long as you utilize the wildlife in Nurn to your advantage in combat and follow the in-game prompts that give hints and tips in completing the missions without fail. Remember to utilize Talion's advanced abilities in combat as well performing simpler moves like stunning enemies and jumping over their heads. Once the main story missions have been completed and all five Warchiefs are no longer a threat, this achievement will unlock.