I think Angron had an ulterior motive with his last stand. He desired to go out with a bang, to ravage and rile up the city states so much that they had no choice but to throw out everything in the arsenal in order to put him down. He wanted to die to end the pain, and used his talents in warfare to make sure a whole world was united against him in a collosal battle. And then, his father arrives and takes him away from his planned death. He have already given up, nothing more to live for, only going through the motions, a zombie desperately seeking the peace for his tortured mind in the deepest dim of battle that never lasts long enough. And if his mind finally blanks out, the Communion is there to drag him back to his tortured existence.