Seeker over Gor. Same increase attack but seeker turn meter increase 30% compared to 15. Foli over roschard 

I could be wrong. Wait for trips to respond but I would have my order go. Seeker Madame Foli and shazar to finish off leftovers

I defer to others as I run an odd resist/CA setup.  I agree with the above advice on seeker over gorgorab.

You got a lot of great champions to push you to high gold ranks.

Zukoku's advise is good. But I want to use Fu-shan over Lord Shazar. Your offense will be, Seeker - Serris - Foli - Fu Shan(Speed Aura). You can use Draco instead of Serris to give you more damage, but Serris can give you more consistent wins against teams win immunity artifacts.

Just be reminded that to look at team power when using debuffers. 200k team power will likely require your debuffers to have 400+ acc to be consistent.

If you can't speed tune your champions to your Seeker, you might want use both Gorgorab and Seeker together. Your team can be like this, Seeker - Gorgorab(Speed Aura) - Serris or Draco - Foli. 

Personally I dont like Martyr on offense, it is slow and  not my play style. But on defense it can work as long as you give her good speed and 400+ res and with Tormin in your team to push away some of the speed teams. If no Tormin, they will just speed nuke your team. 

Here are some idea on speeds in arena base on my observation. In high gold4, you must have at least 320 speed to outspeed most of the teams there. As you get close to platinum, a lot of them, I think, have 340+ speed on their turnmeeter booster. 

In low gold4, maybe, 50% of the time you can outspeed your opponent with 300 speed. And of course, I am talking with 30% speed aura plus the speeds that I said. 

I would do the following set up with your account.

Leader: Lord Shazar - Speed Aura 32%

1st move: Apothecary ------> Turn Meter Filler + Speed Buff

2nd move: Seeker -----------> Turn Meter Filler + Increase Attack

3rd move: Madam Serris --> Decrease Enemy Defense

4th move: Lord Shazar -----> AOE Damage Dealing Attacker + Bombs

By having 2 different Turn Meter Fillers + Speed Buff, Your Lord Shazar can be built slower.

This will allow you the ability to build up more damage + accuracy on Shazar vs. building up more speed on Shazar.

Your Lord Shazar will be able to crank out some crazy damage.