A certain element within the character is amplified, raising that modifier for a number of rounds equal to the character's appropriate base element modifier.
Amplify (Element) I: Raise (Element) modifier by 1
Amplify (Element) II: Raise (Element) modifier by 2
Amplify (Element) III: Raise (Element) modifier by 3
Element Modifier Effects Reference
Amplify (Element) I: (Element) 3
Amplify (Element) II: (Element) 6
Amplify (Element) III: (Element) 9