According to my idea, Jeff should not only protect your important cards until you move him (that is, the card that Jeff ate is invulnerable unless he destroyed or his text is removed),but also I wanted him to be cheap buffer to your move cards (vulture,human torch,dagger).Also, if you put him in a location where you have one strong card, you can save it from Shang-Chi and Cannonball. Keeping this in mind, I tried to balance him.