Protection
Event

Defense.

Cost: 0.
Resource:

Hero Interrupt (defense): When a boost card on an enemy attacking you would be turned faceup, discard it instead.

"No." - Shang-Chi
Vision #18.
Defiance
Reviews

A card many are bound to sleep on at first since it has alternatives, but if you have access to peak at the top card of the deck and these cards are available, they can save you a world of hurt for cheap. It's also a 0 cost card that is going to combo with anything that triggers once Defense events are played, so can be a cheap reliable way to get those triggers without thrashing your next turn like many other defense cards.

This card can also make defense abilities and cards that are looking for you to take no damage, like Unflappable, and make them a for sure bet. So for players, or even just hero decks, that have an dire need to play things on player phase and not burn their hand during the Villain phase, this is the card for you!

Earth Dragon · 1528
This is not as versatile as Preemptive Strike because Defiance cannot be used to redirect attacks to you by the specific wording of "attacking you". Yet it does have some niche use in getting rid of nasty boost effects other than damage. Also triggers Flow Like Water and Electrostatic Armor (since playing a defense event counts as defending even if you don't use the basic defend action). — The_Wall · 134
Think you have to differentiate @Earth Dragon: Can your get your heroes DEF to 4 with upgrades (as thats the highest attack stats for most villains) and you dont need your basic stats? Defiance and other boost card cancellations are a sure thing to get no damage. — zachertz · 13
The best thing about it IMO is that it's a zero cost card; even if none of a player's engine is online, it's always easily playable and has value in all stages of the game. Preemptive Strike has more utility yes but you can only have 3; why not have 3 of both events? I've done it and the villain always hates me for it. — KLSanchez · 15

Much like the same I said from my Preemptive Strike review, but the same principle applies:

The rules change to Defense makes this card much stronger than it looks. It can make you a Defending character long after the basic defense window is passed, but the real power of this card lies in its power to save a Tough card. Effectively, you make a basic defense when attacked by the Villain. This lowers the Villain's attack by your defense. Defiance takes out the Villan's boost card. What does this mean? It means if the Villain's attack is equal to or lower than your defense, its attack is zero. With no boost cards, it will deal no damage. Which means any existing Tough cards you have on you are saved for another attack! I find this card is great in Protection cards that run Tough, like Doctor Strange or Colossus!

I also run this with Tony, using Energy Barriers to deflect the Villain's base damage.

Soulfire · 35