Decorpsinator serum

The Decorpsinator Serum is a concoction that is capable of reviving dead tissue. It was created by Princess Bubblegum in the episode Slumber Party Panic. When she initially tested it on dead Candy People, it was incomplete, and created an army of undead zombies that threatened to destroy the Candy Kingdom. Later on after Finn solves a simple math question, Princess Bubblegum takes the answer, four, and applies it to her Decorpsinator Serum, which finally made it complete. She then used it to resserrect the undead Candy People that had tried to attack earlier in the episode.