Even if you've collected or missed the other skill shots the left crossover shot stays list for a skill shot combo sequence at the beginning of the ball. Shoot it then the upper loop or side ramp, and repeat for up to 6 shots.
You can start Area 51 multiball while one of the Overlord multiball modes is running, but not the other way around.
Soft plunge into the drop targets to get one of the van modifications to boost your next mode, or go for bigger points with a plunge directly to the left outlane.
Soft plunge to flipper for a free shot