Well, believe it or not, but I am just an ordinary LoL player just like most of you guys. I don't even have a high elo or anything like that, but i know my knowledge could help anyone wanting to play for fun.
This is my first guide but I will look forward to creating new ones and updating old guides. So, if you liked this guide to Jax support, please vote and don't hesitate to comment anything about how to make my guides better.

Well, I love to use Jax in the top lane and in the jungle since I started playing League of Legends (middle of season 4), but at some point, I needed to train other roles, and during my adventures in the other lanes, I found out that I am pretty good as a support.
After this discovery I thought: "Jax kills almost every champion easily, so why don't we use him to help feeding our AD carry?". When I tried doing this, I discovered that he can easily wombo combo his enemies while taking lots of damage, leaving the last hit to his ally. That is why I think he is perfect for playing as support.
But even though Jax is a God-like champion, you should never underestimate your enemies. Jax is OP, but does Vayne and other champions.
After all that being said, go try it, help your team, crush your enemies, and never forget to ****ING WARD!!

When the time to kill your enemies finally arrives, you should follow this sequence:

E-Q-E*-W

That way you will be able to burst some damage and stun your target.

*You may cast your E again to stun your target more quickly, avoiding their scape, but if you feel confident, you may also wait till it automatically re-cast

As a support, you should avoid farming, but you may break that rule some times.
You may farm when:
-> your ADC is away from bottom lane AND isn't comming after the farm;
-> your ADC needs healing from your support item's passive (you should go after the cannon in this case);
-> your ADC is dead and you should advance the lane to avoid losing a tower.