I’ve been rereading the grimoire and hoping you guys can help me figure out something that’s bothered me every time I read the books of sorrow. That being: What’s the point of Oversouls when Ascendant realms exist? I know gameplay wise they make for a good wiping mechanic but in terms of lore it doesn’t seem to mesh well with how we know ascendant realms work.
So Oversouls are supposed to house an Ascendant hive’s soul after death right? Allowing them to come back as often as they want, effectively becoming immortal? And one of the many aspects of Ascendant realms are that they also house an Ascendant hive’s soul after death? Allowing them to come back as often as they want, effectively becoming immortal? If these are both true then clearly there’s no purpose to having an Oversoul, as Ascendant hive will be able to die and come back whether they have an Oversoul or not, only being permanently dead after dying in their Ascendant realms.
The only reason I can think of to explain the purpose of Oversouls is that maybe only Oryx and his sisters are able to die and come back without needing Oversouls due to being Hive Gods? And all other ascendant hive still need an Oversoul or they will permanently die even if they are outside their Ascendant Realm? That would mean we’d be able to kill Crota in the material plane if he didn’t have an Oversoul. But if that’s true then why does Oryx have an Oversoul? That being the Dreadnaught. Although that point may be up for debate as some see the Dreadnaught as his Oversoul and some don’t, I don’t know if it’s ever been definitively proven one way or the other.
My take on it, granted without lore backup, is that it’s multiple ways to accomplish the same thing. If something is important to you, you have multiple ways to make sure something works right? For example, writing a paper. You don’t just trust the auto-save, you manually save it as well(or at least I do). This is the same concept but multiplied by a factor of several thousand times of importance, they just have a couple ways to do the same thing because of how important it is.
Hopefully this makes sense, if you want me to dig in the lore to try and find an actual reason, or something that is more based in the lore than this, let me know and I’ll get on that for you!
As far as I’m aware, all Hive can enter the ascendent plane through some means. But, only Hive who have reached the level of ascendent can make a sort-of safe space in the ascendent plane. Then, if they are to get stronger and kill more, they can then, in a way, bind this pocket to a place in the real world. However, from my knowledge, no Hive can have a safe place like the throne worlds of Savathun, Xivu Arath, and what Oryx use to have. These throne worlds were practically impossible to enter unless you were a level of a god and can just travel through the ascendent plane inter-dimensional methods, and even then, it would be a challenge. There throne worlds are practically pocket dimensions granted to them by the Worm Gods when they first made their deal centuries ago. As far as I know, a throne world like theirs has never been made. Now, why does Crota and his sisters not have these throne worlds, well, my guess is because they hadn’t reached the level of godhood like Oryx and his sisters.
As to why Crota is the only one with an Oversoul is actually caused by Crota’s mistake. Long story short; Savathun tricked Crota into making Oryx’s throne unusable. Oryx makes his ship, the Dreadnaught, into his throne world, thusly making it accessible to us. He assigned the Warpriest and Golgoroth as his protectors. He gives Golgoroth a gift (which is actually the wipe mechanic he has in his encounter in the raid). Crota learns of this and gets jealous. He gets his sisters to help him make something similar. Bibbity bobbity bang, the Oversoul became his thang.
Oversouls were created by Ir Halak and Ir Anûk as described in chapter XXXVIII of The Book of Sorrows. Oryx had noticed that they were experimenting with death and the explination they gave to his inquires was that “We propose a method by which Ascendant souls can be detached and integrated into a tautological and autonomous thanatosphere, which we tentatively term an oversoul. Oversouls can be stored in a throne world as a mechanism of enhanced death resilience. As a side effect, new refinements to our Deathsong may be achieved, moving us closer to a generally effective paracausal death impulse.” or as they elaborated when Oryx expressed annoyance at their confusing explination; “If we can separate our deaths from ourselves, and hide them, we will be hard to kill.”
Simply put, oversouls are a way of separating one’s ascendant self from the ascendant plane, and securing it inside a physical throne world, presumably making it so that in order to kill a powerful hive entity, Crota being a notable example, one would have to travel into said entities throne world, being unable to kill the physical being and soul of the entity in a separate place or at separate times. We killed Oryx’s soul forcing him to take himself, and then we had to kill him in his throne world. But with Crota, we had to kill his soul and being in the same fight.
The sisters also claimed it would somehow increase the paracasual lethality of their song, but the mechanics of such effects are unknown.
Also intresting to note, it appears that Crota’s oversoul could be used in a similar way to Oryx’s throne world, and be pushed out into normal reality or Crota’s throne world to cause destruction. Examples include the Crota’s end wipe mechanic, and Oryx’s superweapon causlity bubble.
Oversouls are throne worlds inside of throne worlds, but for souls instead of bodies.
Edit: as you mentioned, Auryx and her sisters constatly killed each other and renturned to the living world. This was because they all had their own throne worlds at the time.