Critical Hit Tank
"The creature weilds a well-worn battle axe and advances toward you with blood lust glowing from deep-set black eyes. Whatcha gonna do?" Says the DM before taking a hearty bite of barbecue chicken pizza.
"I grin threateningly and raise my staff muttering the ancient words to cast fireball." you say and raise your dice in clutched fist.
With a flourish, your d20 skitters across the Formica tabletop almost leaping to its death to floor below. There it is, nearly glowing from the small triangular face staring defiantly toward the heavens. The coveted natural 20. Critical hit.
"The monster is instantly engulfed in an unholy flame that incinerates his flesh and leaves a charred skeleton standing there incredulously before collapsing to the blackened dirt." There is much rejoicing and fluorescent green sodas are lifted to salute your victory.