I have seen on two different occasions, after suspecting it for a long time, that this card only considers the defense value of each character before the fight starts, and does not check the values when it's its turn, based on initiative.
I will get a screen shot soon if absolutely needed, it's just hard to screen shot something like this.

Example:
I play two when it's my turn (with an Eclipse character, let's say Mouktar) and it is opponent's turn, and overall turn is "1".
all the opponents have defense value of "2" and my characters are "0" or "1".
first opponents card activates, and increases his defense by "3". now he has defense "5".
My first activates and only increases my attack by "2", and does not count the defense "5" of my opponent after being risen to this level, which makes me believe that it checks the defense values ONLY when the are played, and does not track it in the fight as defenses increase.

I highly doubt that this is an intentional mechanic of the card, as it doesn't mention when it checks for the defense values.
Also I suck at maths, but I am sure "5" is more than "4", the number which require to add the bonus!

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Eredan Kickstarter

The game mechanisms should take the current defense value at time the card activates. And what you have described is a bug.
It would help if you can provide a screenshot.

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Collectionneur de cartes

I report the problem. Anyway a screenshot is always helpful. Provide it if you can.

I have captured a video, but before posting it, I have a question.
I have experienced this problem with defense of opponent becoming "5" during the turn, but the video I captured only shows a defense "4" opponent.
Does the bonus activates at defense "4", or when says "superior to 4" then it means minimum "5"?
If it means "5", then I have to play a few more games to be able to capture it.
Here goes my video however, not a long one, just captured a couple of rounds!

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Eredan Kickstarter

"Superior to 4" means "at least 5"

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Collectionneur de cartes