Perseverance

In practise, perseverance is a difficult card to make use of. You normally want to play a block card every single turn, and if this is the only source of block that you have drawn then you cannot afford to hold on to it. Thus, unless you are playing a fairly defensive deck in the first place it can be difficult to actually allow this to stack. Note that it does have its purpose, and is particularly good versus the big slime and the Guardian bosses that have huge attack turns In addition to turns where they don't attack at all. Note that the block gain persists throughout combat, meaning that the second time you draw it, it keeps all of the stacks that it had previously.