Yah Ken was the original heel hook king!
There's a very good video on Mir showing his knee bar against Brock. It was actually a calf slicer attempt one that Charles Oliveira uses all the time. It's become one of my favorites although I'm not entirely proficient at it, but it's one of the less technical leg submissions. Heel hooks or ankle locks aren't the easiest to pull off cuz of the sweat and people scrambling...Toquinho makes it look easy.
I learned a bad ass knee bar counter against a triangle that I have yet to pull off. BJJ is such a technical martial arts. It's become so advanced now that fighters have to use more unorthodox submissions to win or chain submissions or they just specialize in one particular submission move and perfect it.
Marcus Aurelius: Tell me again, Maximus, why are we here?
Maximus: For the glory of the Empire, sire.
Baked, not fried... the healthy choice.