Harry Potter's Polyjuice Potion allowed the drinker to assume the form of someone else. It was a complicated, challenging, and time-consuming potion to make and required ingredients such as lacewing flies, leeches, fluxweed, knotgrass, powdered horn of a Bicorn, and shredded skin of a Boomslang, as well as a portion of whoever the drinker intended to turn into.