You can use "Scapegoat" during your opponent turn and then activate this card, even if your opponent had less than 4 monsters, you'll destroy all of them. If you wait your opponent perform his normal summon, his field must be empty for your turn.
Nimble Momonga can summon two copies of itself face-down. If there are just two more monsters on the field, you can destroy the face-up monsters while leaving Momongas on the field.
This card is excellent to use to counter "Ultimate Offering" by destroying everything your opponent summoned.
Similar to Dark Hole, use this card when controlling a number of Trap Monsters (with Imperial Custom on the field) in order to wipe out the opponent's monsters but leave your own untouched.
This card would work very well in a "Ghostrick" Deck because the non-Xyz Monsters can flip themselves face-down.
This card work well with the Subterror archetype as Subterror Behemoths can flip themselves face-down. Also, if you have Nemesis Archer on the field her effect will trigger letting you summon any Subterror Monster from your deck.