Malignant substance
The synonym of non malignant is benign.
The word malignant (evil, malicious) has the verb form "to malign" and the noun form "malignancy."
If it is not known whether a tumor is benign or malignant, it is sometimes referred to as as "mass".
The tests show that the tumor is malignant.
Liquid? maybe?
Malignant would be the main answer, but another possible one is Cancerous.
The word for that substance is SOLUTE. The term "soluble" describes the action, but is not the term used for the substance.
The MRI of the patient is characteristic of malignant tumor. The malignant growth of the industries has spoiled the landscape.
Cancerous.
incense
Transmutation.
Easy: reactivity