I believe Oryx CAN die if he's killed in his realm AND his worm is killed. Also, from the grimoire, I believe Oryx can't "take" a species unless he makes a wound for them on his tablet. This begs the question, "can he take someone who is bound to another realm?" I don't think so. Else, why hasn't he "taken" his siblings in order to control them and gain more power? Another point I'd like to make is that while people are talking about the worlds that Oryx has destroyed, the only one that matters is our world (the world inhabited by the players). Molag Bal invaded our world. Oryx himself never got past the Saturn. And how is this even a point? There are no other inhabited worlds in the elder scrolls lore (I'm talking planets, not daedric realms. Unless you argue daedric realms ARE the other planets, but that's another discussion). For all we know Molag could LOVE destroying whole civilizations on other planets, if they existed. I also think how many people it took to defeat them is a moot point. 6 for Oryx, 1 for Molag... it'd be NONE without additional help. 6 guardians infused with light. 1 human/orc/khajiit/elf who live in a world influenced by the will of the Aedra. So basically all this to say I think a daedric prince could best a hive god. But that's just my opinion. :)

[quote]This begs the question, "can he take someone who is bound to another realm?" I don't think so. Else, why hasn't he "taken" his siblings in order to control them and gain more power? [/quote] He doesn't want to Take them. He brought them back to life out of remorse after he killed them. Although they betray and kill each other all the time, they do it because they care about each other. It's like fighting with your younger sibling to toughen them up. He won't Take them simply because he doesn't want to. He wants them to live on their own.