If i were Luffy i would pick one of these:
- go G2, scream "Law, teleport Killer!" (Shorter than "they gonna do something big!")
then grab Zoro and Kidd and get outta the way with G2. No one get hurt.
- go G4 Tankman, the inflation process smacking all the alliance far far away from the path, do G4 multiple stacking and go Gomu King King King Cannonball and divert the Hakai blast.