The Thresher is a test which all drafters must past. The nature of the trial is kept secret but it is stated that it is "real" and that one out of ten supplicants dies. The test is held in a round chamber with crystal walls and floor, with a black stone disk in the center. The initiate is supposed to step on the disk and meet seven hooded figures, wearing the robes of the seven colors. Each of them wears a mask or makeup in order to mimic a color wight and represents the vice of the respective color. The wights then strip their clothes and present the virtue of each color. Next they aim luxin rays at the stone and test begins.
After the colors flow into the disk, it falls slowly through the floor. The applicant is given a rope with a bell on it. Ringing the bell means quitting and failing the test. Then the applicant is subjected to painful and scary visions, which indeed seam "real". The true nature of the test is to scare the initiate in order to widen the eyes and force him/her to draft. The pulsating colors on the walls are the source, while the black obsidian drains the drafted colors. At the end of the test, the stone is examined and the colors it has drained are the ones the initiate can use.
Everybody is supposed to "fail" the test and quit at some point. Dazen Guile is the only person, who has endured the whole thing, with Kip coming close by lasting whole four minutes. However Tisis is blamed for sabotaging his result, by placing the rope back in his hand, after Kip threw it away the first time.