I recently went through he trouble of making myself a Chaos set, and took it on a FSC run to test it a bit, and I love it already. Though I noticed something weird with it that I didn't actually expect:
While fighting a Trojan, I was getting absolutely wrecked by it, because I failed to dodge one of it's charges. As it hit me, I got stunned and had that weird bug where I couldn't move at all, and I had 5% health left. The trojan hit me again with his sword, and it made the damage sound, and my character exploded the health pips, but I took no damage at all. My shield was completely intact, so that didn't absorb the damage at all.
Does this tie in with the miracle "when the wearer needs it the most" on the description of the miracle cloak? Do they all do this? I have never noticed it before. Is it just something that everyone knows about and I didn't?
There is a small chance for every knight to ignore damage that would kill them wearing any armor.
I don't recall any threads that tried to determine exactly how it functions, but there have been multiple posts mentioning this happening.