The final test... that was a joke. The forth test is to hunt the Coreanus of the Salt Mines. The Coreanus... These are Fierce Monsters unlike any you've hunted so far. It would be wise to take a comrade or you might end up dead. Ken's terms don't say anything about doing this alone so it would be all right to get help from a comrade. Oh, should I have told you this earlier?
After accepting the quest, take the road west out of Horizon. When the road forks head west and when it forks a second time head northwest. Head north into the Salt Mines. Coreanus can be found throughout the Salt Mines. Kill the required number of Coreanus and then return to Guild Official Oveli.
Now, there is only one test left~ I don't know if that's a good thing or a bad thing, but let's get it over with!