One of the things that has been a bit mysterious now honestly has to be the mixed powers so here’s my take on it.
First off let’s begin with what I believe the ‘mixed’ powers are….

I believe the ‘mixed’ powers is one of the biggest curses Great One released unto the world, this cursed two beings; McBurn and Osborne.

The ‘mixed’ curse is the Great One’s way of causing conflict with humanity without it being there, when you think about it you can sort of see how it can be considered one; for starters it gives the wielder supernatural power, for McBurn his is more aligned to fire being able to conjure intense flames without the use of magic, orbment, mana, etc. Osborne however can only be up to speculation, judging from what Rean has, in my opinion it’s aligned with earth wielding incredible speed, strength, sight, etc. Essentially Rean’s mixed powers grants him enhanced senses that’s not humanly possible and judging from this, if we assume Osborne was fully mixed like McBurn, imagine how much more terrifying Osborne can be in ogre.

As we all know, the cost of power is great, and this is where it gets cracky as hell…. McBurn’s issue is that he is so strong that he gets bored, so bored that he only finds a glint of entertainment from fighting strong opponents, this in turn becomes destructive. Osborne’s case however comes with his distorted ideals; wanting to take control of other towns, cities, countries etc to empower Erebonia with war and causing conflict with other countries for his plan we do not understand as of yet.

What both have in common is that both have different ways of causing conflict with the world, they both have destructive natures/ideals. Simply put, the mixed curse is a curse on the world affecting it from the inside and that the reason why McBurn and Osborne are like this is cause of the mixed powers; the curse, brings them onto this route to ultimately cause chaos unto the world.

That’s not all… now let’s talk about Rean here, with Osborne’s heart Rean is given an unstable power however it is in a small portion which would allow him to have much better control over it, in a way this also eliminates the urge to cause chaos… however being the cursed one he is, there’s always chaos with every step he takes.

I’m not entirely done here… let’s talk a bit more about the severity of the curse, if you look at the image posted before, you can see the similarities of the three; both have yellow slitted eyes, both have either a purple-reddish aura or looks like it, and they all pretty much go insane from huge amounts of concentration…. of the curse.

In my opinion, I would say Nameless One had the biggest amount of it pretty much losing all of itself from the curse, McBurn being the fully mixed one still contains it’s original form even after transformation, but what about Rean? Once again this is going to go serious crack territory.

I think the reason why Rean will be stuck in his ogre form is because of the high concentration of the curse his body took from going insane. The area he was in would defiantly contain huge amounts of the miasma/curse which just amplified his power to the point that he wasn’t even in control of himself and the corrupted mana he just released was even strong enough to corrupt Valimar itself. This large amount of corrupted mana being released all at once is so great that Rean couldn’t even get out of ogre form at that moment, why is that….?
Because Rean just became full mixed.