Playbooks

Flood is a three level, one-side concept out of Shotgun Split Slot Open with 20 personnel on the field. The backside receiver runs a solo dig/in breaker across the middle while the frontside stacks a deep vertical from the slot, an out breaking corner route from the outside receiver, and a shallow flat route from the backfield that releases underneath. This is a classic Cover 3 beater that floods one sideline with three defenders stacked at different depths, forcing the flat, curl, and deep third defender to all declare, and the primary read progression works low to high starting with the flat route, working to the corner breaking route, and finishing with the deep shot if the corner defender bites down.
Pre-snap, check safety depth and alignment, since a single high safety rotating hard to the flood side signals Cover 3 and confirms this play is live. Watch the flat defender at the snap, if he sinks too deep to take away the corner route, the underneath flat throw is open immediately for an easy completion. Key the corner route defender, if he stays flat footed on the outside receiver's break, the deep slot vertical will have a soft spot to work into behind him. Cover 4 or Cover 6 shells with two deep safeties can shut this down by taking away the deep vertical, forcing the quarterback to check down to the flat route quickly. Man coverage with a deep half safety over the top can erase the vertical shot, so look for the backside dig route to be the answer if the corner rolls man and leaves no natural flood defender.
Pre-snap, identify whether the defense is showing a single high safety shell, since this concept is built to stress Cover 3 rotations on the flooded side.
If the corner backpedals into a deep third and the flat defender sinks with the shallow route, hot route the deep slot vertical into a comeback to sit down in the window behind the flat and in front of the deep third.
Use this on third and medium to long situations where you need the defense to declare zone or man, since man coverage teams will struggle to match three receivers stacked vertically on one side.
Pair this with Dbl Slant or RPO Peek Slant from the same set to give the defense a quick game answer if they start rotating extra help to the flooded side after seeing Flood on tape.
Against aggressive user lurk linebackers sitting in the flat, throw the corner route immediately off the catch point since the lurk defender has to choose between the flat and the intermediate route, and you want to punish that indecision before he recovers.