HIs mechanic works that you need to do x number of hits to get him to lower his shield, regardless of how much damage those hits do. So you ideally want champs with multi-hit a1s

Once his shield is down, the typical strategy is to hit him with turn-meter reductions to keep him from getting a turn, but barring that, at the very least you want to get a heal block on him so he doesn;t heal back up when he does get a turn.

1) Multihit A1 and 2) don't let him take a turn.  

Okay, we'll start with Blind Seer.  Disable her A2 and A3.  Multi-hit and DEC TM.  These are the two keys for Fire Knight. Seeker for his TM boost to help your other champs go faster.  High Khatun in the lead for her speed Aura and turn meter boost.  Jizoh might be good as counterattacks count towards your hits taking down the shield should you be unable to keep it down.  Other than that, a good wave clearing champ would help

You have some really good champions but unfortunately I am not seeing one that will make a huge impact on the FK. Speed down and multi-hit are your friend. I think the person above has a good plan.