Honestly - a team of 5 level 60s with full masteries can probably one key hard almost irregardless of composition. I'd focus on maxing FB first - she'll last you the longest. Apoth next. Then maybe Fayne.

Trying to 1 key hard is a meaningless goal.  You should be trying to 4 key brutal (or 3 key if you dont play enough to use 4 keys per day).

Your goal should still be dragon progress and farming 12.3.  Lack of 6star champs and Gear is holding you back.

Like Karma said, work on FB first.  Currently she is the best champion for CB you have.  The second you get one of the 4 AOE counterattack champions start working on them.  A counterattack with FB is a great way to rack up damage since FB has a poison A1 she will keep stacking the poisons.  Just make sure she has more HP than your "tank" so she doesn't get stunned.

1. apoth

2. spider

3. fb

Shouldn't I have her in Lifesteal Gear? lol I'm confused.

Thanks!

Yes, lifesteal gear.  But there are 4 counterattack champions that place counterattack on the entire team.  AS SOON as you get one of those 4 champions add them to your CB team.  A counterattack buff from another champion is what will really set FB in motion.

If you ever pull such a counter attack champ, put him in your team. But you can't guarantee that you get one of those. I prefer to have goals where I can influence if I reach them or not. 

So I would suggest to make Apo, FB and Fayne lvl 60 and max their masteries. That will increase the damageoutput of your team a lot, and it makes the heal from the setbonus work. The champs get healed to full life if Warmaster/Giantslayer procs. A lvl 50 champ will not heal enough from the set, the damage Apo or FB deal at lvl 50, without masterie, is to low.

Apoth and Spider are your best choices.  FB and Fayne are far less versatile, and will be of little help in dungeons if you cannot keep them alive.  Short term, the immediate damage boosts you get from them will be nice but Spider and Apo can be on ALL dungeon 20 teams.