import crafttweaker.events.IEventManager;
import crafttweaker.event.PlayerInteractEntityEvent;
import crafttweaker.entity.IEntity;

events.onPlayerInteractEntity(function(event as crafttweaker.event.PlayerInteractEntityEvent){
  entity = <entity:mysticalworld:entity_fox>;
  if(event.player.currentItem.matches(<minecraft:iron_ingot>) && event.target.isEntityEqual(entity)){
    event.player.executeCommand("advancement grant @p only triumph:bestiary/fox");
  }
  else {
  event.canceled = true;
  }
});