Anti-Fire type Team?

So I have been going through the new Event and I’m currently stuck on Ex Hard: Stage 7. I have a trash line up and have been trying to finish the whole event with it, but I just have no luck with stage seven. Which Mercenary should I use to finish up the job?
The stage seven is a complete fire type Team and honestly seems invincible to me…

Here’s my lineup:

If u have rolled more than 3 packs and that’s yr team, consider rerolling .

I have only rolled once and I’m waiting for an Astrid event. In my previous account I had rolled 8 x10 and had only 1 SSR character so I restarted.
As of now I have 9.3k stones saved up, bc I’m a free to play player…