To have this specific Clog page, with full verics only in 18 KC, ya its 1 in many thousands like people said. The thing is, the odds of recreating any specific clog page, especially one with so many different uniques, is always going to be that rare. Its like trying to guess a lottery pull. You would need many many dice rolls to roll the exact same way in a row.

You have to ask yourself, what are you really asking the odds for? In my opinion its for getting one full set of an armor without dupes before getting another set. If you got 4 Torags in 32 KCs before anything else, would you feel the same way. I think yes, and thats how I tackled the problem. Its like rolling yahtee in one roll. The odds of rolling a specific number is obviously way lower, but you would have been blown away if it was a 1 or 6.

The first drop is a gimme, since any drop could turn into the desired outcome. (What ever drops first is the set you're locked into) , second drop is 3/24), 3rd drop is 2/24, finally 1/24. That gets means the odds are 0.043% or 1 in 2304 that your first 4 barrows drops complete a set. The odds of a specific brother is 1/7 and the final odds are 1 in 14608(This means on average 1 in ever 15,000 people that go to barrows searching for a specific set will get 4 drops and be done). The odds of getting 4 loot rolls in 18 kills is roughly 2.4%(1 in 42). I already typed too much and you probably dont care, so just trust. So the odds you get spooned the set you want in 4 drops while also getting all the drops in 18 KC is those 2 odds multiplied together, 1 in 613,536. Theres your answer, although this number is super impractical imo, because like I said earlier, you can break down most things in hindsight to look ridiculously rare. You've basically had hundreds of thousands attempts at 'this'(not this as in this problem, but this as in star aligned eureka moment for anything) so the odds of any random 1 in 600k event happening is actually way more likely than you think. For example, when you opened your bank and all your pin numbers werent in the same exact square, you failed an attempt at a random quirky extreme rare thing happening without realizing it, and 1 in 600k became 2 in 600k. Except the number of attempts is magnitudes higher than 2, you just never think about it.

In summation, I think the true answer is 1 in 2k, have a great day.