Trial of the grasses or herbs was an incredibly painful trial to which young witcher apprentices were subjected. It required the consumption of special alchemical ingredients known as "the grasses" and affected the physiology of the subject.
Reportedly, only three in ten survived the trial; those who didn't survive died in agony, while those who did gained lightning quick reflexes, their signature cat-like eyes, and other bodily enhancements in return.
However, when Kaer Morhen was attacked, nearly everyone, including the school's mages who closely guarded the grasses formula, was killed and thus the School of the Wolf lost their knowledge to create more witchers.
For two days more did symptoms not subside. The child's skin, hitherto drenched in sweat, grew dry and hot, the pulse ceased to be full and firm — albeit remaining of average strength, slow rather than fast. No more did he wake, nor did he scream.
Finally, came the seventh day. The male awoke and opened his eyes, and his eyes were those of a viper...
Though another lab can be found outside the castle and inside a cave to the south, in Witcher 3 Wild Hunt, the player can explore this lab during the scavenger hunt for Wolf School gear and Geralt will reminisce about his past subjection to the chemicals.
During the quest Va Fail, Elaine, Geralt needed to brew the Decoctions of the Grasses. The witchers and Yennefer then subject Uma (Avallac'h) to the first part of the Trial. This consists of administering Mother's Tears, Wildrye Juice, and Speargrass Sap into the veins.
- In the video game, it is during this trial that Geralt's hair is said to have turned completely white. In the books, however, Geralt's hair turned white as a side effect of some "additional experiments" which were performed on him. However both are true due the fact that the ones experimenting on Geralt modified his traits.
- "Trial of the Herbs" is the title of a song by Marcin Przybyłowicz included on the Inspired by The Witcher CD.
- The table on which Uma is operated in Kaer Morhen is named by Vesemir "Sad Albert".
- See the GWENT standalone game version card: Trial of the Grasses