Star Wars: The Force Unleashed

Frenzies occur when you kill multiple enemies in rapid succession.

The frenzy begins after killing 3 enemies quickly and grows X1 for every subsequent enemy you kill after that. Getting hit by enemies will not stop the frenzy as long as you continue to kill enemies quickly.

That being said, you must kill 3 enemies quickly and then kill at least 3 more people. I believe that I got this in the Darth Vader prologue.

the easist way is in the begging of the game when you're darth vader when u get to the bridge near the ending kill every wookie you see