To receive this quest, enter the public quest region at the Ring War Battlefield around 258, -330, -409 in the Great Divide.
The quest is divided into several stages. The mobs required for the stages are dependent upon the current difficulty of the quest.
For a full walkthrough of how this type of quest works, please see our Public Quests guide.
Windslasher posted this tip regarding how to ensure that the x4 boss spawns on the official forums:
|Ring War is actually not determined by time. The victory condition to spawn Narandi the Enraged is: Don't let any of the named dwarves die in the first wave.|
Now, in order to save them all you do need to bring a full raid of people, but that's because the more powerful kromrif will spawn as 'actors' (i.e. they won't be attackable by players, for safety purposes) if there aren't enough players to reasonably engage them.
Possible rewards are numerous and dependent upon the difficulty of the PQ and whether you get a common or rare chest.
See Great Divide Public Quest Rewards for the full list of known loot.
After the battle the field will be scattered with many collectible shinies!