Dont delete events after triggering the event listener. Once they're in the event listeners hands, it's their responsibility to properly clean up the memory.

src/Battling/EventHooks/EventHook.hpp

@@ -20,7 +20,6 @@ namespace CreatureLib::Battling {
             for (auto listener : _listeners) {
                 listener(eventData);
             }
-            delete eventData;
         }
     };
 }