"The 20th Century Achilles" - A criminal claiming to have been dipped in the river Styx obtains some kryptonite and goes on a crime spree. Completely invulnerable, and able to keep Superman at bay, he seems to be an unbeatable foe.
"Mr. Mxyzptlk's Super Mischief" - Mr. Mxyzptlk comes up with a new dastardly plan: he legally changes his name so that Superman won't be able to get him to say it backwards. He then returns to Earth to have a bit of fun.
"Superman Owes a Billion Dollars!" - An I.R.S. employee realizes that Superman is in a spot of trouble. He's been collecting reward money for years, giving it to charity. However, only 15% of anyone's income may be given to charity for tax purposes. In his career, Superman has amassed over $1,000,000,000 in back taxes, and he has 24 hours to pay it before he is punished for tax evasion.
