Hi my name is Lisa and I play league of legends.Jax is one of my favourite champions and I will make a guide on Jax.

For marks I take attack damage because it is easier for last hitting.

For seals I take seal of armor because it is really helpful to AD champs.

For glyphs I take magic resist,But scaling would do if your versusing a ap champ.

For quints I take attack damage.(same as marks)

I take 21/9/0 mastries as it helps for damage and some tank.
Double edged sword really helps because you take additional damage but you do more damage to them.I take 3/4 fury because it is helpful for backdooring and take the point to expose weakness because at teamfights or ganks,your allies deal additional 1% damage to your targeted enemie which helps.

I take brute force and martial mastery for more damage and also spell weaving which helps your do more damage as you are a auto attack champion.I then take Executioner as it makes you deal more damage as your enemie health gets lower and dangerous game as it makes your survive longer at teamfights.After that I take devastating strikes and havoc for increase damage.

In the tank mastery tree I take block,unyielding enchanted armor as it helps you resist damage from poky champs and verteran scars and juggernaut for more health.

I take E first as it helps for defending at early game and then take leap strike next for escaping ganks or for going agressive.I then max W as it gives maximum damage output to champions.Always get R as you do more damage and more armor and magic resist.

I take Flash and Ignite for spells.You can swap ignite for teleport for backdooring and helping allies in fights.