Something won that wager. That is important to remember.
If that thing is Oblivaeon, then why is he destroying it. Oblivaeon wants to be the only thing that exists.
Wager Master warns them of Oblivaeon coming (in his own way) and the powe of the Void is used to fight Oblivaeon.
I like where Alex was going with this. The void being the nothingness of infinite possibility. When someone won the wager a lot of that energy became the Wager Master (all the impossible possibilities) and womewhere the void still exists, and can be tapped into and used.
Scholar meets up with the void, and he can see and use ley lines and can alter the physical structure of things. He builds the stone to do just that.
The Sentinels use shards to become the Void Guard. Are they protecting the Void? Fighting for it? Using it?
IF the Void is energy of limitless potential, then Oblivaeon is most likely looking to destroy things to gain that energy for himself.
If the shards are able to channel that energythen it would make sense that they are coveted and extrememly powerful.
It also makes sense that someone using the void would start to be consumed by it, as the powe of nothingness flows through them it starts to turn them into nothingness. The Void Island could be a manifestation of the Void's natural progression to return everything to itself, or it could be a result of the work Oblivaeon is doing.
I don't think Oblivaeon is the Winner of the Wager. I think he is trying to undo the effects of losing the wager.
I also think that Nightmist, with her training to use magic understands harnessing the power of the void better than the others. When she harnesses the void to pull parts of different realities to our own she becomes trapped in her "mist" state, which is probably not water vapor. Others are being consumed, probably because they are harnessing the power without the knowledge of how to do it.
The intrinsic power of all existance (being born of the void) would lend itself to the blood mage Deadline, who can see the ley lines that shape life and learn to use the actual energy of life itself to boost his harnessing of the ley lines power.
This is all crazy and new, and I can't wait to get more stuff to work from.
TL;DR: I think Oblivaeon was on the losing side of "The Wager", and agree with the void being the limitless potential of nothingness.