When Volibear Imposing triggers ('When an opponent moves to a bf other than mine'), if a player moves 4 units all at once to a different battlefield, does the opponent draw 1 card or 4 cards?

Ruling: The opponent draws 1 card when multiple units move simultaneously to a different battlefield, because the trigger is templated per player, not per unit.

Nuances:

• If units are moved one at a time as discrete separate moves, each move would trigger a separate draw