Ghostspeak amulet or Cramulet or Hard Morytania achievements (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.
Remove any armour or weapons you have equipped, keeping only the amulet of ghostspeak (not a cramulet) and ring of visibility equipped. You may find it easier to attack the priests in the same order as you did during the last time, though they can be done in any order.
The first foe is Snothead. Go to the first grave to the left and say the name of the prophet.
The second foe is Snailfeet. Go to the first grave to the right and say the name of the prophet.
The third foe is Mosschin. Go to the second grave on the left and say the name of the prophet.
The fourth foe is Redeyes. Go to the second grave on the right and say the name of the prophet.
The fifth foe is Strongbones. Go to the grave at the far end of the room and say the name of the prophet.
The use of Dreadnips is also allowed during the battles.
Legacy combat mode can make the fight somewhat easier.
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, or ghostly robes, the priests will start their normal dialogue, and if a dreadnip finishes off the priest while speaking he will drop normal bones, not the bones you're looking for.
If you log out in the temple, you will appear outside, and will need another potion dose to enter again.
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 enter 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 Ghostbusters.