Quest: The Cursed Tribe
Location: Largashbur, southwest of Riften
Level requirement: 9
Go to Lagashbur and defeat the Giant that is fighting Orcs outside the gate.
Talk to Atub in the watchtower by the gate. She will tasks you to find Troll Fat (which is very easy to find, just kill a troll) and a Daedra Heart (which you can buy from Enthir in the College of Winterhold, in the Hall of Attainment).
Return to Atub and give her the items.
Follow her until Malacath tells Chief Yamarz to go to Fallowstone Cave and fight the Giant, and then go to Fallowstone to help him out. This cave is north east of Lagashbur, above Riften.
In this cave will be two Giants and two Cave Bears up to Giant's Grove. Here you can make one of two choices. You can kill the Giant that Yamarz was supposed to kill, and then have to kill Yamarz, or have the Giant kill Yamarz and then you kill the Giant. After killing the Giant, you will take his hammer back to Lagashbur.
Return to Lagashbur, talk to Atub, and put the hammer on the shrine when prompted.