GMMichael
Guide of Modos
TotMank you.This is mostly an issue with minis. With TotM, you can just say they move away.
Besides an "army" fitting into a cave . . . I hear that 5e doesn't require squares. So don't use them, and stopping in a square is no longer a problem.. . . an army of undead in a cave*. So what happens when a panicked ghoul moves through undead allies' smoke filled (heavily obscured) squares to escape the cleric but runs out of movement in a tunnel packed with other undead allies before they find a free square?
If the above suggestions (above posters included) don't cut it - the army of ghouls use a portion of their movement to throw the fleeing ghoul back at the cleric. No squeezing needed.