"RAWR!" means "I love you" in kaiju.
A 6 on the MGF would require you to pay 6 courage and/or stars, if you are using the Hero. Or for example, 3 regular soldiers, 2 stars and 1 courage (if you have the Hero).
When advancing into a sector with a sacrifice requirement, you still need to sacrifice the required specialist. The Hero cannot replace such loss.
So the hero cannot save your sepecialist. Ok, that's what I thought. Omaha Beach has been my most played map so far and you're supposed to kill a speciailist if you roll a 6 on the MFG die. I wanted to make sure we were playing it right.