When this card is activated, its activator can Chain a card effect that Special Summons "Protector of the Sanctuary", which will prevent the opponent from drawing any cards as a result, while their entire hand is still discarded.
Alternatively, if the opponent added a card during a Chain or via a card effect (either of which just resolved), one can respond to the resolution of that Chain or card effect with this card first, before Chaining "Droll & Lock Bird". This will produce the same effect as above.
Virus Control Decks can use this to their advantage. While a Deck Destruction Virus is still in effect, use this card to cripple your opponent's new hand. If multiple Viruses are active, your opponent's hand may be emptied altogether.