Don't waste your time on any of the rares - with the exception of leveling them as part of the Rhazin fusion, as you've clearly already begun doing.

With regards to your epic champs - you have a fair number of pretty good ones! Kinda surprised you haven't got any legendaries yet - bad luck I suppose. But you've very smartly avoided most of the common mistakes people make.

I would get Khatun maxed - she's amazing just about everywhere until you get to Arbiter.

Ultimate Galek is quite good for Spider as well - good candidate to level for that purpose.

Fahrkhan the Fat is a really good CB team attack champ. Highly recommended.

Other possibilities:

Vrask is a fairly good healer for most fights, I'd argue better than Apo - although since you've already got apo maxed, it may not be worth leveling another healer. 

Fayne is quite good for CB, but without an unkillable team she dies fairly fast.

Toragi the Frog can reliably put poisons onto CB, and has some good healing as well.

Spider, excellent dungeon aura and skillset.  Will be best short-term getting you to dragon20, I would prioritize that over FK13.  Also, is great in Arena as the debuffer in speed nuke strategy.

One champion that has helped me a lot for Fire Knight is the Runic Warder, which I see that you have

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You don't even need to get him to 6 stars (I have left mine at 5).  Focus on HP and speed, and his goal is to bring in his 15% reflect damage to everyone, every 3 turns.  Essentially for the FK it makes him automatically lose 5 hits on his shield whenever he has his turn.   Getting the FK shield down makes the fight much easier.  The Continuous Heal and 50% decrease attack debuffs are just added bonuses.  

Thank you everyone for the input! I will definitly focus on runic and spider ultimate galek :)

FYI: Spider needs cooldowns to be booked, but at 60 you can use as dungeon lead everywhere.  And Ult galek (maybe even at 50 only?) with spider, gorg, MM, armiger will take u far in spider dungeon if not through 20.

I think their are 4 different strategies people use vs. Fire Knight.

1. Counter Attack

2. Rally

3. Turn Meter Control

4. Reflect Damage

You don't own any Team Counter Attack hero's.

You own 2 different Rally hero's - Fahrkhan the Fat & Catacomb C.

You own 1 Turn Meter Control hero - Armiger

You own 3 Reflect Damage hero's - Terror Beast, Warden, & Runic Warrior

Out of the above, it seems like a Rally set up or Reflect Damage set up might be your ideal options.

I guess the tie breaker will be how fast are your hero's?

If your hero's move 3 or 2 times vs. Boss 1 time, You might want to use a Rally set up.

If your hero's move 1 time vs. Boss 1 time, You might want to use a Reflect Damage set up.

Reflect damage doesn't stack, one champ with that ability can enter any team, you don't need a whole reflect damage set-up.