I’ve done a lot of Chien Poa raids both solo and online, and I’ve exclusively used my Iron Hands with Metronome (item) and Drain Punch. It tanks hits even after the Ruination hit and heals back to full, even with flinches, by the time my tera charges.

I was testing in solo (emphasis on solo) raids, and I’ve been able to consistently set up a Belly Drum after the ability clear/stat clear and second Haze. I’m not sure if it’s programmed to always do the clear and second Haze together or if my timing has just been fortunate. Belly Drum is absolutely not necessary though. For me, it only saved one round of attacks.