How good is Spider-Man’s Spider Sense? I had a quick look at the maths here, but I’ve had time now to do the complex maths around crits, fails and rerolls.
Long story short, as well as being better than 4 dice in expected damage taken, it is also better than 4 dice in chance to take X damage.
Every possible combination gives Spider-Man a lower chance of taking X damage by up to 4.2%. He’s currently one of the top 5 characters in terms of defense. Exactly where he places depends on what you are facing, but he is in the same conversation as Cap, Black Panther, Iron Man and Captain Marvel.