Lucian falls off late game as that his kit gets over whelmed by the enemy team. He doesnt have as much burst as a Caitlyn would but if the team peels for you it make life much easier. Remember you can not carry late game so you will have to have your team with you but you will be able to duel easier.

Aggresive- If you choose to get youmuus first, its best to go aggresive once you have serated dirk. The armor penetration will help you early in game. Try to play a little more aggresive as you will have more advantage. If the opposing adc comes back with a bf sword play safer then as that you will not have as much damage input into your skills and aa but the armor pen should help better.