Given how powerful the level 5's are, it almost seems hard to believe that there could be monsters strong enough to truly challenge them.
Even the eye in that dead end was scared of Malik.
Not to mention Deus's power, even at level 4.
I hope there are limits to his powers. If he can just go back in time and smother a baby in its crib to prevent a present day troublemaker there really is no greater power.
I mean, who's to say that S Classes are the strongest monsters coming through the rift?
I get that Malik is like top of the line, so much so that he clapped Goliath in seconds. But imagine Deus trying the same thing, I don't think it would work (I could totally be wrong though), it would probably take him far more time. Malik just happens to be old, has a power that does good AOE and Singular DPS, while I'm sure Bernhardt (arguably hinted at being stronger than him) is the opposite, good Singular Burst and less so AOE. But I believe they are both special cases, as even Alexis, a Level 5; had a rough time with Goliath (albeit only slowed her down) and was easily shot put into oblivion by our possessed MC.
Back to my main point you're right, none of the Monsters we've seen so far OTHER THAN the Apostles have come close to even being considered to be able to clap rather than just slow down a Level 5. If I'm not mistaken I'm pretty sure the Monster that Tiffany got her powers from was from an Apostle, as it was the strongest corpse Xanthe had ever come across, more so it was beyond S Classification. I'm assuming that very Apostle also was the one that annihilated Zack and his entire team to the point where they are STILL injured to this day, but it should be noted that Zack was regarded as not even the strongest, this is still the only legitimate case of a Level 5 being injured (not just slowed down) by a Monster.
To expand on this, what if that corpse wasn't an Apostle? We know that there are S Classes, but what's to say that there aren't Monsters MORE CAPABLE than those, but less than the Apostles? Someone like maybe Valravn at his prime or Mommy Monster, that have a ridiculous level of intelligence and know so much about their world that they have provided a bigger lore drop than all of Xanthe's brain throughout the entire game. There's also the Rebis, which doesn't seem like an Apostle, but also is the genius of the race, I mean a Level 1 MONSTERFIED DERYL could progress all the way to Level 3 in a little over a month, what's to say his ancestor Monster isn't capable of furthering himself to beyond a Level 5?
I do believe it was mentioned that the Avatars that the Apostles descend down in can only stay for so long, but have the full power as if they were actually there (case in point WHY they can't stay for long). We know that Level 4 Ella was EASILY stricken with fear at the 7th, and that very 7th annihilated the 3rd. So while the Apostles aren't ranked in strength some of them easily clap the others while some of them also stand above of them. Take the 1st for example, it took both the 3rd and the 4th to restrain it, and Mommy Monster even mentions that the Order and Power? 1st and 2nd would make the ultimate "spawn" of Superhuman. I'd wager the 7th (Dark Lord), 6th I believe it was correct me if I'm wrong? (Master over Space) 1st (Authority/Order) and 2nd (Power?) Are amongst the Apostles that would EASILY be a larger handful to most Level 5s, and that's not even if mentioning their Arbiters can also combine their efforts to make a spawn (both combined powers like our possessed MC put in with another duo of powers).
Now I don't know how power works for when an Arbiter enters your body. It could be like an Evolutionary state (hence going from Lvl 2 to beyond? Lvl 5 I think it was stated?) and your at the peak of your powers for a time. Or the Arbiter was weakened compared to it's max potential due to the "vessel" not being strong enough to contain them, almost like an Avatar I'd assume (contrary to Mommy Dom's belief, I doubt their Apostle's Avatar's could use their ALL OUT powers in limited state). Now what strikes me as weird is why hone a Superhuman to vessel an Arbiter? Is it because Superhumans are inevitably going to become stronger, and they realize this as a way to corrupt them to their will early on (which would also explain the higher corruption at higher evolutions)? Or is it just because the Arbiters can't have an Avatar like the Apostles?
Who knows, but to your point it's worth mentioning that if a Level 5 becomes corrupt enough, they too can become a Monster, this making a Monster capable of beating a Level 5 Superhuman. I think Deus is a special case, and remember; his power either comes directly, or BRANCHES OFF from a Lord in some way. Which means one of these Lords (probably the Twin of the 6th, the 5th? i.e Space Time) would be VERY powerful amongst the Apostles, probably even more so than current Deus...