RuneScape how do you get a skull above your head?

Going into they Abyssal Dungeon ( Zamorak-Mage Mini-Quest ), the same dungeon used for Runecrafting, you will be skulled on entry.

Beware! If you are skulled, you will lost all items if you die, unless you have Prot. Item prayer on, you will save 1 item, that has most value in a general store.