Terrible CQ , the first (and maybe the last) CQ that Qin Shi Huang can't solo .
Taira buffs herself with an NP charge every turn as long as she doesn't get hit by a NP , which means that servants with NP that doesn't deal damage (such as Orion and QSH) will suffer from endless spamming of Tiara's NP which removes their buffs
Not to mention that Orion and QSH are buff centered servants and cannot protect themselves from buff removal.
The only way for Orion to protect himself is by using Necromancy and from there this battle is a RNG sh*t show.
So if not two of the best solo units in the game can't solo this , who can?
1. Servants that can constantly stun Taira thus limiting the using of her buff removal NP , such as Kama and Van Gogh
2. Servants with excellent survivability and class advantage against Taira such as Ganesha
3. Strong solo units with powermod from this event such as Cu Alter and Taira (in Taira's case she also has 200% anti-Genji niche powermod)
All of those mentioned servants must be at level 100 with high NP level (unless you are using necromancy) , not suprising but all of them are the peak of soloing.