*Last item can be a thornmail, or an infinity edge. That is up to you, or your opponents.
*You may want to use ripose instead of burst of speed. Burst of speed is a good skill for tower-destroying, creep killing or if it's used after lunge, it can be used as a pursue skill. Or simply, you can use it in any melee combat. The boost is short, but useful, but if your opponents are like draven or catlyn, who use basic attack frequently, you may choose to max out ripose after lunge, so that you can deal plenty of magic damage to your opponents when they are not able to damage you at all :)
*You may wanna use exaust instead of flash, but frozen mallet will surely help you more than exhaust.