User blog comment:Zathronas/Analysis by an author: Volume 2 episode 11: No brakes/@comment-3146930-20141024021616/@comment-10380701-20141024033833

She actually has two methods of building them up: Attacking and getting hit. I have a strong elaboration on it on this thread.

In fact, Monty himself states that her semblance is literally a SFIV super/ultra meter.