I usually turn my back at boosting, as most things come in time but that Special Delivery (Kill an enemy with a melee attack when landing from a Man Cannon.) sounds a pure chance event. Headlong and Spire it would have been possible on, just looking at 3 maps walkthroughs I can't see it happening. You could play 100 games and never get anyone close enough to a man cannon landing spot to melee them.
edited it in... screw it, if any party need another head you can add me GT: PureNomad