After you helped deceive the opposing faction in An Imposter, your next task in the Oblivion plugin Windfall, you now have to identify and neutralise the source of attacks that have been happening on the main road out of Windfall.
This mission is the same for both Varo's Knights and The Righteous. Speak to Helena to start it for the Knights and Marvel for The Righteous. After getting the quest, it's suggested to ask around in town for more information, as neither Helena nor Marvel have much information. Frillia and Ozkar in the Commerce District are the usual sources.
If you speak to Frillia in The Weary Traveller, she suggests you speak to Ozkar. She also tells you a way of preventing the Goblins from returning; namely by taking their sacred relic, but leaving the Warlord alive, so that the Goblins believe the area to be cursed.
"So, rumor has it that goblins are behind the attacks. It is true that it is just rumor. Of course it may not be Goblins. But so far, Frillia does seem to know all the best rumors. I'll need to plan my actions very carefully. "
There are a number of ways of doing this. First, entering the caverns and killing the Warlord, and probably everything else. You can also steal the sacred item at the same time. Secondly, you could sneak through all three zones of the cavern complex and steal the Sacred Chalice. The final zone of the dungeon, Hard Luck Deep Caves, contains a lot of water; the Warlord is on one of the islands near the underwater entrance to the room with the Sacred Chalice.
Once you take the chalice, your log updates.
"The Chalice of Power? This must surely be the artifact Mirisa told the barkeep about. I need to get out of here without killing the Warlord for the rumor of the place being cursed to succeed."
Return to Helena or Marvel. If you didn't kill the Warlord, they are not happy, even if that was a better method. If you did kill the warlord they consider that a better solution.
Helena gives you 75 Gold if all you did was take the Chalice, 175 Gold if you killed them all, whether or not you took the Chalice. Marvel gives you 60 Gold for just taking the Chalice, and 140 Gold for killing the Goblins.
Both Varo's Knights and The Righteous want you to do the same thing for this quest.
"I have been asked to find the Varo's Family Signet Ring. If it has never been found despite others having searched for it, it seems unlikely I shall fare better but I'll wait and see. However, since the others were simple messengers, it is also unlikely they lack the skills needed to do a proper search of the area."
Inside the offering box is Count Alconius' Key and a Note; read the Note and take both items.
"I have found the key to a chest in which the Signet Ring can be found. There is no chest here. I should search the manor thoroughly, the chest must be in there somewhere."
Now head to the front of the keep. There is a Paint Horse here which you can take if you want.
Inside the Main Hall of the Keep are two Bandits and a dead body. The dead body is that of a previous searcher sent by Brend. On him is a Note saying he won't need any protection, as the only thing he may encounter will be Rats. The keep is being raided by Bandits though, so this was a bit inaccurate.
As well as the two in the Main Hall, there is a Bandit in Brend's Bedroom, two Bandits in the Barracks, the Bandit Ringleader in the Count's Bedroom and another Bandit and a Bandit Hedge Wizard in the Under Floor. There is also a Rat in Stilus' room and another in the Under Floor.
"I have found the chest said to contain the ring but it is empty. I must report this to Helena/Marvel."
Also on the Desk is The Diary of Count Alconius. You can read this, but take it also as it is one of the items required in the quest The Historian.
Return to Helena or Marvel. Each takes the Note from the Count and Helena you 200 Gold, Marvel 150. This is the last assignment you will get from Helena or Marvel; you now need to go see Ophia for your next one for the Knights and Elvetta for The Righteous.
You will now need to help keep the Imperial Legion from interfering further in the succession on Windfall Island in A Forgery.