Your units with Killer have +1/+1.
Amplify 2: Give one of your units Killer.
Card sounds may differ from in-game as they get updated.
Killer - A unit with Killer can make one special attack directly against an enemy unit. This can be done the turn it's played, and can target any unit, regardless of Flying, Aegis, or other special abilities.
Amplify - Cards with Amplify will let you repeat their effect when played if you have the extra power specified by the Amplify number. It is optional and may be used more than once.