I've peppered my thoughts about the Prexxor-Blight situation on this blog and the Chaotic discord throughout the years. It's been a minute since the last time I brought that up here though. Also, it's been a while since I posted here at all (the Obama post doesn't count), so I felt like jotting down my notes on both those topics. Mainly their nature, headcanons to fill gaps and where they could head from there since last Gannon spoke of new episodes, he wanted a continuation. Alright let's go.
Prexxor was weirdly labeled as a past location in the cards. From what I can tell, that was the plan but apparently it fell apart and the location became someplace in the present. Further backed by Garv's reaction to Tom explaining the Blight situation. He didn't say anything about Prexxor not existing or having life long ago. Also, the fact they had two other good times to address it being in the past if that were the case. First when Crellan broke out Prexxori in the dromes, and second when Hotekk started the time travel fiasco by gifting Tom a Dranakis Threshold. Good job, Hotekk.
I also don't see the OverWorlders not stopping the Blight as an issue because Prexxori are mostly feral, and unreasonable. Not even Raznus could negotiate with them. I imagine they have someone like Blazier monitor the chasm every now and then, but between the Prexxori's behavior and the Blight settling in, they didn't need to care much. Also, assuming Blight Flight happens by episodic order, the M'arrillians were invading.
Time for more writing weirdness. The show painted the Blight as some kind of virus on Prexxor. An idea that didn't go much of anywhere besides Garv giving tom a jab to kill it. As far as we were told, it just seeped up from the depths of Prexxor and thought it would stay a while. All the while, it burned every living thing it touched into dust. What I'm about to say is all headcanon just based off my own thoughts about the Blight, and another creature who'll come into play here.
In the episode Stelgar Strikes, we get a look inside Mommark's lab and at the star character as he escapes and terrorizes Pouril Forest. Mommark's helpers and the main boys manage to stop him and he winds up flushed away into the UnderWorld, where Rothar is there to tell him his tribe has cookies and the OverWorlders don't. Despite Maxxor himself telling him to just stop, and knowing it risks banishment, Mommark has been creating these problem creatures. Or they're just weird. Stelgar isn't even the oddest, look at Maglax.
You can tell where I'm going with this. Either before or during season one, Mommark developed the Blight for whatever twisted reason. Since they call it a virus, maybe it was a giant bioweapon. Or maybe he just made it because he was bored, it's Mommark. Either it also got out, or Mommark got rid of it, afraid it'll be the final nail in the coffin with Maxxor. He pulled a Stelgar and tossed it down under, thinking it would die in the barrens of UnderWorld Territory.
It didn't. In fact, the Blight found a passageway back to the surface when an earthquake broke some ceiling and connected the underground to Prexxor Chasm. This next part I wanted to apply my talented art skills to.
And the rest we see in the show. Blight burned Prexxor unstopped until Tom finally decided to do something about it because Maxxor sure wasn't. Whether or not Maxxor found out, the Blight's gone and for his sake, Mommark won't try to make the Blight Junior... His second card's named Clonemaster, so probably not. As to why the kids' scanners couldn't scan it, whatever chemicals Mommark made the Blight out of just caused interference.
I think that covers everything. If I forgot something, I'll add it later. Feel free to shoot your own relevant questions.