Debuffs are effects that will harm any characters. Some do immediate damage like Burning or Chilled. Some make them weaker like Exposed or Slowed. And some like Combo Setup make your enemy do more damage to your characters. There are ways to prevent Debuffs: Using supplies or having a character with an immunity to a Debuff like an Asgardian or a hero with Unbreakable Skin. Using Panacea Injection will immediately remove all Debuffs.