Witch's Potion

Start
Talk to Hetty and ask her to tell you more about the dark arts. She will if you give her four things for her. Go talk to Hetty with all the ingredients and drink from her mixture to complete the quest.
 * A rat's tail : Obtained from killing a rat. (Only while on the quest)
 * Burnt meat : You can get these from various cooking locations or killing monsters that commonly drop burnt meat such as imps (Fish or chicken does not count as burnt meat).
 * Eye of Newt: This can be bought from the magic shop in Port Sarim for 3 coins.
 * Onion: pick one from a field, farm one or buy one from another player.

You will be rewarded:
 * 325 Magic experience