The phrase "playing mischief with" can be replaced with similar expressions that convey the idea of someone causing trouble or creating chaos. One option is "wreaking havoc," which suggests a level of destruction and chaos. Another phrase is "making mischief," which implies the intent to cause harm or trouble. "Stirring up trouble" is another synonym that implies someone is intentionally causing conflict or disturbance. "Causing mayhem" and "spreading chaos" are additional options that convey similar meanings. Ultimately, all of these phrases suggest that someone is intentionally causing chaos or harm and should be addressed or stopped before they cause further issues.