A synonym for mastery might be:
instinct
involvement
expertise
bossiness

i believe the answer is inference

answer: ok heres what i got on google

explanation: to recognize illness in frogs, toads, newts, or salamanders, look for the following signs:

inactivity or unusual behaviors. the first thing you might notice in your amphibian is abnormal behavior or appearance.

gradual or sudden weight loss.

body/abdominal bloat.

skin blotches.

eye cloudiness.

edema.