Prototype 2 Walkthrough - Mission 11 - Orion Phase Two

Let us murder things in variety of ways. And I'm sure nobody expected that plot twist. Not.

[@KainPrime]

Basically you need at least one to perform the devastator. If other two are full, it just has the extra punch.

[@NthDoctorWho]

Ah...cool

[@NthDoctorWho]

So, you have three Devastator Bars, yet when they're all full, doing one empties them all?
or can you do a Devastator when the first bar is full, then what are the other two for?