The ATK gain is actually a crucial part of the effect: What actually separates this card from other generic effect-negating cards like "Effect Veiler" and "Breakthrough Skill" is that this card can be activated during the Damage Step. Use this to your advantage.
Use this card on your opponent's "Shooting Star Dragon" when they move to attack your "Sun Dragon Inti". Because the negation effect of "Shooting Star Dragon" could not activate, the destruction effect of "Sun Dragon Inti would" destroy "Shooting Star Dragon" when targeted, and inflict at least 1650 points of damage to your opponent.
This card is best used with monsters you control with negative effects, specifically those with effects that affect them during battle, such as "Panther Warrior" (would negate his need to sacrifice a monster to attack), "Chainsaw Insect" (would negate the effect of drawing), or "Goblin Attack Force" (would negate its mode-switching effect after it attacks).
Use it on your own "Red Dragon Archfiend" to keep its effect that destroys other monsters you control from activating.
Use "Forbidden Chalice" on a depleted "Light and Darkness Dragon" to reset its ability to negate once the Chalice wears off.
You can use on either "Submarineroid" or "Sonic Shooter" while they are attacking directly. The attack will continue and will inflict damage equal to its current ATK, not its original ATK.
You can use this card with your "Il Blud" when its about to be removed from the field; the Zombies Special Summoned by its effect won't be destroyed.
You can use this card to bypass ATK decreasing effects like that of "Super Vehicroid - Stealth Union" and use all of its ATK.
Use this card with "Machina Force", so you do not have to pay to attack with a 5000-ATK Monster.
You can use this on a face-up Toon Monster when "Toon World": on the field is at risk of being destroyed to prevent it from being destroyed along with "Toon World".
You can also use this card against all of the forms of "Yubei".
It is recommended to use this card on Spirit monsters that have trigger effects, such as "Dark Dust Spirit", "Tsukuyomi" and "Maharaghi", because their effects will already be resolved when you activate this card.
This card can also severely cut down the attack of an "Evil HERO Dark Gaia" since it needs its effects to maintain its ATK. This will make its new ATK become 400.
You can target a "Gladiator Beast" monster to prevent it from getting its effect. "Forbidden Chalice" will also negate the tagging-out effect, although the the effect of "Gladiator Beast" may still be activated (so that the "Gladiator Beast" monster is meaninglessly returned to the Deck).
This card works well against continuous effect monsters like "Jinzo" which will give you a turn to activate a Trap(s).
This card can be used to break an attack lock made by two monsters who protect each other, such as "Marauding Captain" or "Command Knight". Negate the effect of one of the monsters and attack the other, as it will no longer be protected.
Use this card to negate the effect of "Blackwing - Vayu the Emblem of Honor" to Synchro Summon while its on the field. Then Special Summon again once its in the Graveyard.
Use this card in a "Fairy" Deck. During your turn, negate the effect of "Archlord Kristya" so that you can Special Summon monsters. Because while "Kristya" is on the field, it's likely your opponent will have avoided setting anything up that would allow him to Special Summon during your turn. Meanwhile, you have cards like "Athena" and "Soul of Purity and Light" to build up a bigger field, and the ATK of "Kristya" becomes a massive 3200 - Enough to destroy just about anything that would have gotten past the Special Summon lock of "Kristya".
This card can even be used against "Archlord Kristya", opening a window for your Special Summons for a turn.
Use this card upon activating the effect of "Kuraz the Light Monarch"/"Delg the Dark Monarch" so that they attack in the same turn they activate their effects and increase their ATK to 2800.
Cards like "Elemental HERO Neos Knight" and "Vision HERO Trinity" that are very powerful on their own with 2500 base ATK, but cannot inflict battle damage, are great targets for this card.