As for instance, take a look about the attack skills of Lord Yarkan. He has a skill which will trigger with each 25% HP loss. Those parameters at the back are literally mob IDs.
Just get his refobjcommon and char lines, get the skill IDs from his refobjchar line, search for those skills at the refskill table and look for the monster IDs within the skill's param1 to paramX range.
Here, for making it simple: