Official Riftbound ruling
But can I activate Kayle’s empower ability even if she’s already empowered?
Yes.
Kayle’s empower ability can be activated any number of times. If she has less than 3 empowered statuses, she will become empowered. If she has 3 empowered statuses, the ability can still be activated but nothing will happen when the ability resolves.
Riot's question and answer, word for word, from theVendetta Rules FAQ and Clarifications
