Malphaestus
Touched by the Apocalypse
Destroying the railroads and whatnot could also be arranged. When I say "cut off" the oil supplies, I mean gassing their colonies, desposing of the bodies, and destroying the equipment (which would be the loudest part of the ordeal, really). This wouldn't require a navy, as I would have crippled their supply at the heart. Assasinating the family was in fact, part of the plan as well, though I would insure Lastor was not only loyal to the cause, but stocked to take on the other realms.
The Titan of Lastor would probably be the peoples' preferred successor to the Empire of Oros, however it is unlikely that his rule would be any different to that of the Imperial Family. You'd have to find some sort of outlier faction amongst the Orokor, because most of them see the Titan of Lastor as the God amongst Mortals that he is made out to be.
The colonies are overseas. And if you plan on gassing civilians I am not letting you across the waters. I'll just pirate the oil convoys for myself. Or even better, block the Orosian navy from reaching the convoys as I spur them towards independence.
The Empire of Oros is more than versed with conquering former colonies and dealing with known terrorism at the same time as they're protecting their convoys with fleets of Iron-clad warships and patrolling their skies with airships that literally poop out resources by the second. Their problem isn't power, as they have more than enough of that, it's about where their power is represented and seen. After your rebellion showed the Empire of Oros just how vulnerable their oil convoys were, they reinforced their protector fleets to counter your people and the innovation you stole from the orosians. They also increased their security protocols.
Of course, because they centered more forces around the oil convoys, that leaves other imports all the more vulnerable, such as fabrics and spices.
That being said, open and clearly visible terrorism will be difficult. Automata are vigilant protectors and can get quite adamant in their search to uproot evil. The best would be to stick to the shadows until the crucial moment.