You have 3 Titans. You should know you can Regen just by dropping your bubble. Ghorn is the only exotic besides maybe icebreaker or thunderlord you should be running in that fight. The only time I even use my primary is to clear the rooms- and fatebringer does a pretty good job of that to begin with.

Yeah it is, if you takes turn 2 ghaj shots is enoguh to down crota. No other weapon does that. If you want to run a super smooth ce you will use ghaj, primary exotics make little to no difference.