is not a planeswalker. If he ever left Phyrexia, he would probably lose nearly all of his power. I imagine him as some dessicated thran-oid; suspended and encased in machines. Perhaps his body is gone?
I don't know. But I can tell you, that Yawgmoth himself will never leave Phyrexia. He's got the power of a planeswalker, which by the way is extremely intense. They're gods in a way, don't forget. Urza needs nine planeswalkers to invade Phyrexia because Phyrexia is so horribly unfriendly to anything living, regardless of planeswalking ability. in fact, I'm fairly sure that nothing living will remain that way in the 9th sphere.
Nine non-phyrexian planeswalkers in Phyrexia, can probably be assumed to have the total power of about one or two. Yawgmoth could kick any planeswalker's arsze alone, simply because he is the equivalent of something that thankfully could never happen: a Phyrexian planeswalker. But When 9 of them come in, well, that will be fun to watch.
[Edited by MrXarvox on 12-30-00 at 05:02 AM]