Generally I like to play lucian very aggressively, using my dash to get in range to attack the enemy champion and proc his passive early, which combined with the fervor of battle mastery, can yield to lots of damage early. Your basic general combo at late game is eqweq, starting the combo with your dash to put it on cooldown, as every proc of your passive reduces the dash cooldown by 2 seconds (if used on enemy champions), and if they flash just simply throw your ult at them and flash/dash again if you're out of range.