This card has no particular time in which it needs to be activated. Because of this, the best time to activate it is whenever it is targeted by a card effect like "Mystical Space Typhoon", because you will destroy 2 cards, and get one to your hand.
This card can prove quite useful for fighting against a Synchro Deck as most Tuners have considerably low ATK on their own, with most of the "Elemental HEROes" you can target with this card having higher ATK. So you can use this card to destroy an opponent's Tuner monster before they use it for a Synchro Summon. If timed properly, this card can completely stop more powerful, popular Synchro Monsters such as; "Shooting Star Dragon", "Red Nova Dragon", etc. that all use low Level Tuners with low ATK.