Well Jax is my favourite player in th league! The reason? He is the best. Jax is a player that needs almost everything(attack damage,ability power,attack speed etc.) The first item you need is the Dorans blade which gives attack damage,health and lifesteal.Then you will need the boot called Ninja Tabi that increases the dodge chance. After that you need the Guinssos Rageblade which gives attack damage and ability power. It has also attack speed stacks. Next you will need The Hextech which i think is the most important item for jax. It's ok if you have a large amount of attack damage and ability power...But how can you survive a gang?! You must have health. So you can buy the Rylais Scepter. The next item is of course the phantom dancer...The mere hits the most kills :) .Finally if the game runs smoothly you have to buy the Mejais Soulstealer.It gives ability power stacks(max stacks 20)if The game doesn't go that well you should try buying an infinity or a phantom...