Superman is vulnerable to Krytonite an irradiated ore from his home planet of Krypton. He is powered by a particular wavelength of light which happens to be rather abundant in our sun. Kryptonite either destroys or interrupts this because it's radiation is in a band which is similar to sunlight, but causes a different process to occur. In other words, the kryptonite radiation "chases out" the sunlight. There are different spectrums of Kryptonite and its effects on Superman are as follows:
Green Kryptonite causes a Kryptonian's body's cells to deteriorate, similar to radiation poisoning in a human being. Exposure to Green Kryptonite causes a Kryptonian to lose all its powers at -1cs per round. They also loses 1 rank of Strength and Endurance (with its loss of Health) per round until death occurs at Sh-0 Endurance. Removal of the Green Kryptonite enables a Kryptonian's body to regain lost ranks at a rate of one per round.
Red Kryptonite causes bizzare changes in a Kryptonian's body at Un rank. Changes in the past have included a beserk-madness rage and personal shrinking at a In rank. It is up to the game judge to assign an effect at the time of the exposure to Red Kryptonite. These changes last for one day per round of exposure to the Red Kryptonite.
Gold Kryptonite robs Kryptonians of all super-abilities and powers and they then have the same stats of a normal human of the same height, weight and build for fifteen seconds.
Blue Kryptonite is toxic only to Bizarro creatures. Exposure to Blue Kryptonite causes Bizarro to lose all his powers at -1cs per round. He also loses 1 rank of Strength and Endurance (with its loss of Health) per round until death occurs at Sh-0 Endurance. Removal of the Blue Kryptonite enables Bizarro's body to regain lost ranks at a rate of one per round.
An enchanted piece of Kryptonite has effects similar to a hallucinogen, until Batman finds another piece which cancels out the effects of the first piece. The first piece is a silver crescent. The second piece is a lavender round rock that fits into the crescent.