This card is activated during your Main Phase 1 or 2 and creates a state that lasts until the end of your turn. If “Spell Canceller” is Summoned after this card was activated, but during the same turn, the state it created is not negated and 1 monster will return to your hand if destroyed during this turn.
If “Banisher of the Light” is on the field, a monster that is destroyed will be removed from play and cannot return to your hand since it never went to the Graveyard.