Take a Tier6 prot warrior (and his Kara-geared hunter alt), a Tier6 holy priest, a Tier4-ish feral druid (and her blue-geared mage alt).
Boredom was what led us to Molten Core, really. That, and curiosity. "I wonder how far we could get if we tried to three-man MC?" Turns out the answer is "Quite a lot further than we thought possible".