Talk to OSRS gold him and he will inform you that you'll require some Precious Metal, which can be dropped by Trolls on the island also is untradeable. Trolls are just around level 25 - 40 and fall the metallic everytime. Get ten of them and bring them back . Now you have to smith the metals into a body for the creature. Nowadays you have to produce legs from boards. Get 20 planks and use a hammer and a few nails on them to create four legs. Get about 10 cowhides, tan them, and then put them together using a needle and series. Now Willus would like you to build the head.
Behind the castle is a ladder that leads underground. Go down it and you will find 3 paths. Take the path in the center and you're going to discover a big open space with a bunch of level 250 demons. Kill them and it will drop its head. Utilize the head with a few cloth (you want 10) and then cover it with a needle and string. Receive a staff from Zaff or a different participant and use it with the mind to turn it into a head on a stick.
Being it to Willus and the creature will be completed. Obviously such monster's do not just come to life. Willus will give you a letter to buy RuneScape gold bring to Merlin requesting that he helps to bring the creature to life. Merlin doesn't want to encourage the creature, so bribe him with 50gp. He gives you some Magical Essence and informs you it can be smithed into a heart. Use it using an anvil to get a Magical Heart. (provides 500 Smithing experience)