Talk to Dr Fenkenstrain at his castle to the northeast of Canifis.
Tell him "Yes", "Braindead", and "Grave-digging".
Decapitated Head
Equip your Ghostspeak amulet or Cramulet
Talk to Ghost Gardener who is in the Northern part of the castle
Ask him what happened to his head.
Lead him south to the Haunted Woods.
Dig at graves until Decapitated Head is found. You can talk to him to get directions.
Pickled Brain
Head back to Canifis pub and purchase the Pickled Brain by trying to take it or use Telekinetic Grab to grab it from the table. It's much cheaper to just buy it.
Use the Brain on the Head.
Arms, legs and torso
Go back to the castle and go up stairs.
Search the west bookcase for The Joy of Gravedigging and you will find a marble amulet.
Search the east bookcase for the Handy Maggot Avoidance Techniques and you will find the obsidian amulet.
Use the marble amulet on the obsidian amulet to get the star amulet.
Head east of the castle to the tombstones.
Use the star amulet on the far east tombstone, push open and climb down.
Kill the Dog-Woman experiment for the Cavern key.
Follow the North West path and unlock the gate.
Search the chest and go up the ladder.
Dig at all 3 North tombstones.
Lightning
Lodestone back to the castle and talk to the Doctor.
Give him all body parts, a needle and 5 thread.
Talk to the Ghost Gardener for the Shed key.
Search the cupboard in the shed for a brush.
Take 3 canes from outside the shed.
Use each cane and bronze wire on the brush to make the Extended brush.
Go upstairs and use the Extended brush on the East fireplace to obtain the conductor mould.
Make the conductor at a furnace with a silver bar. The closest Furnaces are north of the Lumbridge Lodestone.
Go back to the castle and go up stairs.
Go up the ladder to the south.
Repair the Lightning conductor.
Lord Rologarth
Talk to the Doctor.
Go upstairs and use the ladder in the centre of the castle.