Galactic War
You don't need a whole army of sectorians. You can defeat the humans with your own personal squad, you get ready to travel to earth. Your squad has the fastest, strongest and smartest sectorians in all of sectoria and you are confident you can win using just them.
You leave for earth quickly after making your decision. When you are about halfway there you see that earth has sent a massive army to attack sectoria. But this is not a problem, you are confident your army can crush the humans easily. you send a message back to sectoria telling them to attack the humans fleet with everything you have. Now you can sneek onto earth and kill there leaders without worrying about the armies. But your home may need you to go back and help them.
You leave for earth quickly after making your decision. When you are about halfway there you see that earth has sent a massive army to attack sectoria. But this is not a problem, you are confident your army can crush the humans easily. you send a message back to sectoria telling them to attack the humans fleet with everything you have. Now you can sneek onto earth and kill there leaders without worrying about the armies. But your home may need you to go back and help them.