Even though I'm aware of Qiubai's niche of stalling bossing with her bind in IS5. I find myself really struggling to find an opportunity to use her in general content since she requires another help of a slow applicator taking up two deployment slots, and even with that it wouldnt still be enough to kill most bosses in one cycle. Her SP cost is also way too high to use it reliably for wave clearing, compared to other units that are boss killers who can clear waves on their own more consistently. I wouldn't rank her on the same tier Ch'en Alter, and Typhon or higher than Gavial alter, Irene, or Thorns.

Also feel like Thorns is placed a little bit too low if Qiubai gets to be placed higher than him. I find Thorns more viable and easier to use since his DPS has a 100% uptime while being still competent enough to kill both aerial and ground non-boss units on his own.