Ghostspeak amulet or Cramulet or Morytania Tasks (up to Hard) (Note: If you have the Cramulet, it will have to be dismantled so you just wear the ghostspeak amulet, otherwise the goblins won't drop their bones. Or you could take off the amulet after speaking to the ghost and before fighting.)
You will see the ghost of Hopespear, the goblin prophet. He will tell you a story about a battle between the goblin tribes; he will describe his vision from the Big High War God about how the goblins must stop fighting. Once you tell him that you have been to Yu'biusk, he will tell you that in order to free the souls of the goblin priests, you must complete a ritual of which includes killing the goblin priests to retrieve their bones and bury their bones in Yu'biusk. However, to retrieve their bones, you must defeat the goblin priests without use of weapons or armour.
If you log out in the temple, you will appear outside, and will need another potion dose to enter again.
If you defeat a goblin priest using any weapons, armour, or use any magic spells or magic abilities, they will not drop a bone. You may not use Summoning familiars, either. If you continually aren't able to get Snothead to drop his bone, talk to Hopespear to make sure that you told him that you have been to Yu'biusk. It is not required to remove the ghostpeak amulet and ring of visibility in order to get the bones to drop.
The use of potions and prayer is allowed during the battles.
The use of Dreadnips is also allowed during the battles.
You don't have to defeat all the priests at one time. You can leave the crypt and continue where you left off, but you will need another dose of transformation potion.
If you are wearing the cramulet, ring of visibility or ghostly robes, the priests will start their normal dialogue, if a dreadnip finishes off the priest while speaking he will drop normal bones, but these are not the bones you're looking for.
Once you have all of the bones, you can teleport out of the crypt. If you exit through the door, you will appear outside of the goblin temple, in the cave. You may bank if you wish. Find a Fairy Ring and teleport to Zanaris. Enter the fairy ring code BLQ to be transported to Yu'biusk. You may bury the bones anywhere in Yu'biusk. Each bone buried will give you the corresponding amount of Prayer experience. (See chart above) Attempting to bury the bones in the region of Yu'biusk accessed during The Mighty Fall does not work.
Congratulations! Miniquest complete! You are rewarded 13,750 Prayer experience!
When talking to one of the goblins in the temple they will say "Me hear ghosts in the temple crypt! No one sees it, but sometimes they hear it. 'Wooo... Wooo... ' It say." In which your player can respond "Who ya gonna call?" which is a reference to the 1984 film Ghost Busters.