I’m no expert on carnage. I’ve played it very little compared to brute. I’d say, though, that having at least 1 point in Resolute advance lets you break root with charge, not just to have root immunity. Defiance is a decent heal for the entire group, and when I played carnage I didn’t find rend flesh worth it, but other people more experienced can give their thoughts.
These days I use this spec in brute: Conqueror - Feat Planner - JoharAoC