After rewatching the scene, I can confirm that Maga-Grand King and by extension, Magata no Orochi's laser, is capable of Durability Negation. Borderline One-Hit Kill on the latter's part.
This is due to Shin's statement and its portrayal back in Episode 2 where after being hit literally only once, Orb's Timer started blinking. Sure, it could be because MGK is naturally stronger, but remember that Orb also survived his Maga-Perforation attack.
Not only that, but it's also the only thing capable of damaging its own armor. You could argue that it's because Orb may have been weaker at the time, and that his Sperion Ray only struck the inside of MGK. The latter argument works, but the former, maybe not so much.
Still, though, I'll leave it to you guys to decide on whether this is legit or not. Maybe wait for Akre to provide a better explanation.
On other notes:
- I've also found that Ginga may have Power Nullification. First episode, his shield seems to warp Darambia's electricity which he gathered and seemingly erased.
- We need a better way to solidify Low 2-C Ultras. King's already secured. But I can't say the same with Geed; we might need to improve on his Low 2-C justifications.
I will provide my proposal, at least:
Universe level+ (Is capable of harnessing the King Capsule, which contains a greater and more concentrated amounts of Childhood Radiation; in turn, they are the materialized particles of.King's very own essence which are capable of binding the universe together as well as restore its space-time)
Not only that, but it seems that by releasing the Childhood Radiation from the capsule, King is able to reform his body. Which is more of a plot hole, but I think it should work, still.