When I did this build i tried to focus on staying alive. Meaning jax is a very weak champion so I wanted to create some survivability. In early game you should take it easy and collect some cash and levels. Reason for that is because jax is really easy to take down in early game, of course it depends who you playing against.. Firstly you should always take boots first, some people would watch my build and think its a failure. In truth this build focuses on doing melee damage and using mostly the first 2 skills. I'm not much of a fan of the counter strike skill because you have to take hits before actually can use it. So I decided I focus on first 2 skills so I can do fast damage and if that doesnt work I can retreat and wait for others. So firstly take berserker's greaves and then buy BF sword to get damage. After buying those items you can start building the rest while checking out your opponents. If they have alot mages and really hard to get even close to them get banshee's veil for protection. Vampiric spectre is useful in games because you can stay lanes for longer. Well I can explain more than this because I want to leave rest to your own imagination ;D this item build gives you around 3200hp and 377dmg and like 80ap. And never underestimate crit.