From a Tidal Wave, Facing Lines, or other applicable formations. 
 Arm Turn 1/2; Center 6 Cast Off 3/4 as Very Ends 
  Counter Rotate 1/4;
  resulting Center Wave Hinge & Spread (to become Ends of Parallel Waves) as Others do the Centers part of
  Cast A Shadow 
  (Leaders Cloverleaf as Trailers Extend; Hinge; Extend). 
 Ends in Parallel Waves. 
| |   |  |   |  |   |  |   |  | before Relay The Shadow
 |  | after Arm Turn 1/2
 |  | after Center 6 Cast Off 3/4
 as Very Ends Counter Rotate 1/4
 |  | after Center 4 Hinge & Spread
 as  Others do the Centers
 part of Cast A Shadow
 (done)
 | 
 | 
 Note: To smoothly dance Relay The Shadow, those doing the 
  Hinge & Spread often lightly tap hands as they go by each other, rather
  than pause at the handhold, Hinge, then slide apart. 
Relay The Shadow anyone Criss Cross [C2V]:
 From Facing Lines or a Tidal Wave.  Do a Relay The Shadow, but those 
  doing the Center's part of Cast A Shadow (the anyone dancers) do
  the Center's part of 
  Criss Cross The Shadow [C2] 
  instead.  Ends in Parallel Two-Faced Lines.