about mystical space..its a really common card, does it only destroy a card on the field and not negate a card being activated even though it is a quick play?

(for example.) my opponent is going to activates fissure and then i play mystical space, since it is a magic card.

now the argument is that it may destroy the card, but the effect still allows fissure to destroy my monster..I say it negates the cards effect since it does destroy the card..

need help..

Mystical Space Typhoon will destroy the card, but will not negate it.

Once a normal (non-continuous) card is activaed, the card doesn't need to stay on the field to resolve. The card needs to be negated. This is why you can activate Graceful Charity and chain Emergency Provisions and still gain 1000 LPs.

No card ever "negates" anything unless the card specifically states so.

Some cards CAN be prevented from resolving successfully like Continuous Effects.

In terms of attacking, it's the same thing. Even though cards like Sakuretsu Armor, Gravity Bind, and such do not specifically say to "negate" the attack, the attacked monster (if it would normally die in battle with the attacking monster) will survive since Damage Calculations were not reached yet.