Go to the main node at the right in order to get the warmonger. You can use the rail or win a few seconds by using the glitch above the second node (in which you can get the swingshot).

Activate the first key node, near this main node. Spamm with warmonger : it's probably the most effective (and easiest).

Return to your base (the teleporter is faster) then activate the west key node (spamm again).

After the cutscene has completed, go to the planetary defence center : do not shoot, use two glitches to go above the shields and skip some fights. Then destroy the mini grungarians on the inferior platform and kill the two demolititionists and the two other grungarians on the main platform. After the cutscene, kill the monster (spamm) and activate the planetary defence center with two shots of warmonger. Cutscene.

Reboot sequence : as for korgon.