"That's right. Maybe that's why they're so intent on spreading it—to amplify whatever signal they were spreading in the first place. Now that Phyrexia's left the Multiverse, they've gone out of range. The oil keeps listening for new orders but isn't receiving any. Why's that? Well, there are a host of possible answers all worthy of study. However, in my expert opinion, I think all of it was tied back to Norn. A megalomaniac of that scale wouldn't want anyone else to have control over her army. I imagine she was the only one who could send orders—and, further, that the oil is rendered inert without her. Wouldn't want a rival seizing control when you've lost contact, would you? So, without her . . ."

- MARCH OF THE MACHINE | EPISODE 10: THE RHYTHMS OF LIFE

In my articles about designing March of the Machine, I talked about the scope of the story. The Phyrexians invaded every plane of the Multiverse; managed to compleat some amount of the natives of these planes, turning them into Phyrexians; and then fought tooth and nail to take over the planes, in many cases coming very close.

- DOING THE AFTERMATH

residentpianist asked: Maro directed me to you--is the Multiverse infinite?

I often say there are “countless” planes. A vast number, and some sources claim there are infinitely many. There are more worlds than anyone most mages will ever have practical need for.

- A Voice for Vorthos