Not sure if the developer sees problems with the game here or not. At any rate, my level 4 guy just played a 6+ health quick card and my health did not go up, and there's no doubt about it as my total hearts were over 11 and I had 6 health, got attacked and was left with 3 and rather pissed, because it ended in yet another tie death, which btw, happens ALOT on the last fight. Ugh.

The card does not add 6 health. It sets your health to 6. It's only useful if your health is below 6.

And with cards that increase hearts, it's possible to heal above your current maximum. That just adds more hearts.

That card is crazy good! But then again the Apprentice is OP OP the more lifegain items you acquire in your run.

It also has "quick" which means your health is set to 6 before you are attacked :)