Hey OP, I think Kram is spot on here looking for a Seeker. He would realal be the difference between making an easier 1 key team, specifically in the Bateater shell. This shell is basically the team that Skadi linked above, but that team doesn't have Seeker and needs a 326 Maneater and a 299 Maneater and still only works on UNM.
However, there is another team you have available with your specific champs that, with decent gear, can one key. Instead of using Seeker and Painkeeper and fast Maneaters to get a DPS to 2:1 speeds, you can use Ally Attacks to kind of simulate that 2:1 speed. So this team would use the Easy Double Maneater shell and 3 DPS, specifically using Geomancer, Kreela and Fahrakin.
https://deadwoodjedi.com/speed-tunes/easy-double-maneater/
Did a couple takeovers after Geomancer had his guaranteed shard event where I was able to pair him with double Ally Attackers in good gear and see a 1 key.
What is nice about your particular ally attackers is that if you time their initial skill usage, you should have Inc Attack/Inc Crit Rate and Inc Crit Damage up for most of the fight, Fahrakin can bring some extra poisons damage and is ofc bringing your Dec Def, and you can override Fahrakin's burn with Geomancers burn.
Anyways, that's what I'd run given your current champs, Easy Double Maneater with Geomancer, Kreela and Fahrakin. :)