In the early game, you take the control of the Big Gun. You know, the Interplanetary Defense weapon which you were sent to destroy as Bitterman. This time, they let you play with it, in order to take down as many Strogg as possible, but with the objective of destroying a big blast door in order for your team's Cool Airship to deploy on the planet.
The final Nexus levels. Especially the last Nexus level and your last fight against the Makron. You get to destroy the Nexus core as it constantly spawns hordes of all kinds of Stroggos, from simple soldiers to Heavy Hovertanks. Not to mention that the pose that Kane strikes during the ending, upon destroying the Nexus, looks utterly badass.