Alchemy

Officially, alchemy is the process of creating concoctions using various ingredients to better human life. While true to some degree, the study mainly provides numerous advantages on the battlefield, ranging from blasphemous to completely ethical.

Many mages practice alchemy in addition to their main craft. However, this is not a requirement, and the best in the field are often individuals who dedicated themselves solely to alchemy.

Source
The destruction of the Lady of the Land resulted in her power seeping into the world's plants and minerals. Every unusual property in an ingredient is a fragment of her personality. For example, herbs that heighten healing are from her compassion while poison is from her spite.