[hailene]

Consider that during the Heresy, for example, Angron was capable as a human of wiping out entire company sized units

Could you give me the quote on this? I know we've seen Angron butcher his way through a lot of Space Marines (slaughtering them left and right with each swing of his axes), but I don't know if we're given specific numbers.

The Iron Hands lost an entire company described as being 1000 strong to the presence of a simple daemon.

I haven't read too much IH fluff. When did this happen?

fluff that 13 of the greatest soldiers in Khorne's followers short of An'ggrath or Ka'Bandha were cut down by a measly 100 space marines doesn't ring true.

Rock paper scissors sort of deal, I think. The daemons have incredible fighting potential, but the Grey Knights were deliberately created as their hard counter.

 

[hailene]

IIRC, he was able to cut himself a path to Rus

I wasn't able to find any particular listing of Angron single-handedly killing his way through a thousand or so Space Marines, but in Betrayer, he started the fight within weapon's reach of Russ.

"Both Legions tensed. Thousands and thousands of warriors clutched bolters and chainweapons tighter. Lhorke had even taken a step back, his joints loud in the sudden silence. Russ felt no such hesitation. He drew his blade and launched at Angron, only to be met with the World Eater’s axe blocking the blow."

In regards to the IH fluff, it's in the Damnation of Pythos.

Haven't read it. And from what you've said, looks like I saved a couple of hours.

I originally thought about that - but if all it took would be 8 Grey Knights (it's not clear if they were all Terminators or not) to kill Angron, who is one of, if not the greatest, of all of Khornes followers, then all it would take is a combat squad of grey knights to cut through a full fledged warp tear.

Most definitely took more than just 8. Every GK on the field that didn't die in the initial charge fought Angron. Almost definitely over a 100 of them. Plus they didn't even kill him, simply banished him.

Also take note that Angron absolutely murdered 5 of the GK terminators without a modicum of effort. ADB described the slaughter of the 5-man squad with less effort than a man would need to kill an insect.

I think it was Hyperion's breaking of the Black Blade that gave them any hope of victory.

Don't forget how rare a Grey Knight is. All of them are psykers--which makes them incredibly rare already. Then of those, only one of a million psykers brought to Titan actually become a Grey Knight. A million out of a million. Out of a trillion souls, only one is worthy to become a Grey Knight.