 The fourth season of the American animated television series Adventure Time , created by Pendleton Ward , originally aired on Cartoon Network in the United States . The series is based on a short produced for Frederator 's Nicktoons Network animation incubator series Random ! Cartoons . The season debuted on April 2 , 2012 , and the season finale was aired on October 22 , 2012 .
 nobody is immune from the effects of the power of the heart.
The season begins with Finn and Jake traveling to the Land of the Living to find a cure for the Ice King's heart disease. They come across a magical artifact that