Two angry divine entities of absolute destruction fight to the death.

[GardenBlossom]

Here we go. Let's do this.





Battle takes place in Heaven as Olierus tries to taqke down it's ruler, a being of absolute destruction. However, no other beings will intrude on the fight

Mastema

Olierus

Speed Equalized

3-C keys but they get access to the Spear of Destiny and the Astral Breaker respectively

Epic Battle Theme

 

[Promestein]

How... did I miss this?

 

[Promestein]

Alright, let me divide this into distinct chunks.

Statistics:

When it comes to AP, Mastema has a pretty big advantage. Olierus is around baseline or a bit higher, but Mastema scales quite a bit higher, being much stronger than characters who are much stronger than baseline.
Astral Breaker may be able to reach the same level of power as the Spear of Destiny, which would offset this, though the Spear is more hax than it is AP. I'm going to assume Astral Breaker would reflect this. This is assuming that it would be able to amp up to properly face the Spear of Destiny, as Mastema is an order-aligned individual.
Skill and Intelligence:

In terms of combat skill, I think Mastema and Olierus are about equal. That being said, Mastema has access to Logos, and instant, invisible attacks that can number in the trillions. She has Luminous Fist there, too.
Mastema may have the advantage in terms of longer-trem planning and scheming, as she's used to managing Heaven's government and leading it in large-scale warfare. Olierus' strategies sound similar to Uriel's, and I think he'll have a hard time finding any issues in Mastema, especially any emotional ones.
Even if Olierus is brilliant when it comes to magic, Mastema is one of the greatest of Starcross' agents/mages. I think she'll have the advantage here, but I don't think that's a big deal; that just affects how she'll be able to respond to certain forms of attack. Skill-wise, Mastema is a jack of all trades, so it's not like sh really has any shortcomings.
Abilities:

Ah man, this is where things get hard, but interesting. I'll go through this one by one and compare what they have.
Olierus' Watcher of All is superior to Mastema's Aeon and her other perceptive abilities, as Olierus would be able to detect Beelzebub while she's using Dream Evil, whereas Mastema would need some time to figure it out. But Watcher of All is a bit more circumstantial.
Olierus' Tempus Infinitum is an issue - it's very powerful, but Mastema is no stranger to attacks that come in such extreme volumes, and she can dish out the same with Multiplicative Onslaught. It's especially potent when used with Logos and the Spear of Destiny, as she can unleash all these instant attacks that warp reality in a variety of different ways as she delivers them.
Olierus' time stop, though, could be an issue. I dunno if we judge time stop potency by range. I don't think we do, otherwise Dio's time stop wouldn't be resisted by a bunch of people and targeted time stops won't be as potent. But if we do, no one in Starcross can stop time across multiple universes.
They can kill each other; Mastema's got her Low-Godly (specifically inner world Regenerationn) and Zero Heart, while Olierus has Types 5 and 8 Immortality. Mastema can destroy universal laws with the Spear of Destiny, while Olierus has his Apeironegation. Neither of them will be dying instantly, of course, but they can kill each other.
Olierus has Type 3 Concept Manipulation, while Mastema has Type 4, but I've never really been sure where Agency Concept Manipulation falls, and Type 3 may be more accurate, so who knows.
Miscellaneous subjects:
Absolute Barriers, big resistances, blah blah blah. They can both punch through them.
Ollierus can duplicate himself more than Mastema can duplicate herself.
So... inconclusive?

 

[Uninown]

They both have their respective arsenals, and this is a pretty damn close fight, I'll give that.

Both Olierus and Mastema have ways of taking eachother down, as well of persisting through pretty well (Inner world Low-Godly stuff for Mastema, Immortalities Type 5 and 8 in Olierus' case)

I think Promestein has covered up pretty much anything I could possibly say, so I'm also leaning towards this being an inconclusive match given the circumstances, at least for now.

 

[GardenBlossom]

Blah blah blah agreement and...eh, only part I'd say is sorta wrong is Olierus AP but even then, I really didn't specify very much on how he scales to other characters, and even then then...you're still right in that he has less AP than Mastema sooooo...Incon because I agree with the conclusions preceeding this post made by Promestein.

 

[Imouto-tan]

I concur there isn't much that could be said that would change the outcome from being inconclusive

 

[ZephyrosOmega]

Incon FRA