Ah, that's what that was, thanks for mentioning it. At 1st thought he did the combined jet missile, then turned that as just a setup for a combined bazooka or gatling gun.
Waaaaiiiiitt...Is the reason we didn't see Luffy's hands, is because they're gonna come out in full Gear 2 + Gear 3 + CoA Glory?! (remember, he can run gears on individual body parts)
For the boys and girls who haven't been paying attention G2 + CoA = Red Hawk. And G3 + X = Massive X. Therefore G3 + Red Hawk = HOLY SHIT! Is that what Caesar is about to take to the face?!
ALSO: What would happen if Luffy was to perform a Red Hawk on Caesar, Gigant or otherise? Wouldn't the fire cause Caesar to detonate into a massive fireball (as Usopp attempted to do) and pretty much use up his entire body/strength momentarily? Cause that would be awesome!!!