Using a Flamtaer hammer is highly recommended in case the minigame is unpopulated, as a regular hammer is insufficient to build the temple alone. An additional 13,000 coins (or 5,312 on the Grand Exchange) allows you to buy a Flamtaer hammer from Razmire.
Enter the ruined house in the south-west of Mort'ton. Search the shelf on the wall. Read the diary. After reading the diary, the quest is started and you are able to create Serum 207.
If you didn't bring Tarromin potion (unf): Pick up the empty vials (can be filled in the house north-east) and search the smashed table for 2 grimy tarromin and one grimy rogue's purse.
Serum 207
Make two Serum 207 by adding clean tarromin to a vial of water and then adding ashes.
Use one dose on Razmire (afflicted) in the general store. (4•1)…
4
What are all these shadowy creatures?
1
Yes, I'll dispatch those dark and evil creatures.
(Recommended to not use official Mort'ton temple World 377 yet to not get interrupted talking to the NPCs, until the step with repairing.)
Kill five loar shades and pick up their remains. Note: any shades that you killed before talking to Razmire will not count.
Return to Razmire and give him the remains. He may require more Serum 207.
Right click and open his General store, buy an Olive oil.
Open his builders' store, buy 5 timber beams, 5 limestone bricks, 25 swamp paste and optionally a Flamtaer hammer.
Use the serum on Ulsquire Shauncy, located in the house east of the general store. Talk to him with Loar Remains.
Talk to him again and ask about the remains and the temple. (1•2)…
1
What did you find out about the remains?
2
What can you tell me about that temple?
Repairing the temple
Head north-east of Mort'ton and repair the temple until you reach 100% repair and at least 20 sanctity. (Recommended to use official world 377.)
Light the sacred altar in the centre of the temple (or wait until someone else lights it if you don't have level 5 Firemaking)
Use your olive oil on the flame to make sacred oil.
(Recommended) Use Serum 207 on the flame to make Serum 208, which permanently cures NPCs.
Quest points
2,000 Herblore experience
2,000 Crafting experience