Note that your opponent must have exactly 4 cards in their hand when you activate this card, not more or less. However, they do not need exactly 4 cards when you resolve this card.
Use "The Eye of Truth" to see your opponent's hand before you use this card, in order to get an idea of which effect may be more damaging. If their hand contains mostly Spells/Traps, choose this card's second effect; otherwise choose the first.
Use a Virus Card in order to control your opponent's hand before activating this card. This strategy may be quite a shot in the dark, due to not guaranteeing that your opponent will have exactly four cards in their hand. But if that kicks in, you may prevent your opponent from activating Spells/Traps if you're running "Crush Card Virus"/"Deck Devastation Virus", or if you're into "Eradicator Epidemic Virus", prevent your opponent from drawing even further.