Blackrock was simply friggin' cool.
Every ROT gain (maybe all gains) was actually variable 0.2-0.5, instead of 0.1 gains.
However, the dev's were damn sneaky. It was only valid in a region around the blackrock elemental spawn areas in T2A, which you can't gate/recall out of.
So, you had to sneak (or run) in there, get your gain, and then sneak (or run) out, hoping you didn't get pk'd.
That was the ultimate fun of it. Risk (getting pk'd - come'on. This is siege.) against reward (perhaps 0.5 gain on whatever skill you are working).
Innumerable times, I'd get a 0.4 hiding gain, only to get pk'd by Krystal, or barely get away from a pk squad.
I risked little, except death, since I carried nothing of value. But it was hilarious none-the-less.