“Muggles” is a nice way of saying “pick.” WR1 and WR2 run in tandem up the field, with WR2 breaking out to the outside just as WR1 makes his “in” move. If the safety picks up the pick by shifting to the outside, the middle of the field is open to either WR1 (if he’s able to regain his speed) or WR4, who’s just then cutting across the middle for a solid 10 yard gain.
The secondary play here is for the left side receivers to draw all the attention away from WR3, who, if everyone else is covered, is streaking across an empty field with room towards the sidelines. Not a huge yardage play, but can potentially break with some good blocking upfield.
Personnel: Try this one with your fastest guy at WR1; it might help enduce confusion when he suddenly stops his route to pick WR2’s man.
Pre-snap reads: drop down to WR3 on the blitz.