I would suggest posting a screenshot of your full champions roster here. Maybe you are sleeping on a gem there.

Spider 19 is Force Affinity.

You need to use Spirit, Force, or Void Affinity heroes against it.

Otherwise, you will have issues.

Your Magic champions will have a very tough time winning.

You only really need to do Spider 19 once just to unlock stage 20, so you can just try your luck with using Draco and Royal Guard. Hope for a good run with no weak hits. 

In doing so, you may also try adding a booster like Apothecary (which can be built with the least HP to bait initial hits away from Draco/RG), and add someone who can mitigate damage for a little while. I'm sure you can finish it, just try stuff out. Like I said, you only need one good run.

What about the pumpkin will he help and i have scly?I think i need to pull a good void but im just not lucky on that :(

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Lxzy is correct!

Stage 15 - 17 - 20  need to be Auto Friendly.

To Claim Arbiter from the missions, You have to be able to auto 10 times on those specific stages.

Stage 16 - 18 - 19 are 1 time dungeon fights.

I recommend manualling the fight to ensure you win. 

All you have to do is beat them 1 time.

Than you will never go back to them ever again.

If I was you, I would try what Lxzy is saying.

You will never fight Stage 19 again.

It is just a road block to your true destination.

If you can just get lucky in 1 fight, It would be dream come true.

Yeah - Stage 20 is Spirit.

All your heroes are magic - You will have way easier time vs. Stage 20.

Stage 20 is the most important stage for farming good gear + final test in Arbiter mission.

Do you have the hero Renegade by chance? 

i would use masoleum mage as a tank slash healer draco as ur debuffer royal guard just as good as a coldheart i would also use scy of drake and tundra

This is just to give you something to consider. You have 2 of the champs on my team, but you can get an idea of what each one does and find someone on your roster that are similar or even better.

Here is the team I used to get past 19.

Tyrant lead, M.Monster, Scyl, Rhaz and Armiger 

Im not familiar with your champs on the top row, besides Scyl, but maybe your Ult Galek for HP Burn, someone with some TM to help Armiger, Zargala for dec def

Mage Draco and RG  have been mentioned above so they would probably be the core, and just need to add to them to help you survive the one win you need.

THX all

I notice that you have a 6* Armiger.  You may want to try him for some turn meter control with his A1. He's also enemy max hp damage on his A2 and spirit affinity. Should do really well on spider 19.

Guess I should have refreshed before posting...

Armiger is a spider god - turn meter manipulation is so much more important than burning the adds. Build him properly so he crits. AOE HP burn is also fantastic - Ultimate Galek makes such a difference in spid runs.

I built Armiger just like they say but him alone with out another turn metter champ just wont cut it on 19 and ULT galack is good till 15 then he dies no matter how much hp u stack on him also he dont boost on force is my most night mare at this time.