MAJOR SPOILER: It is not meant to be completed. It's the new 4* unit on peak performance. Interesting traits: The new boss tears def down like Levi/Patrone, has the DPS of Hermes, heals 1700s like Sunny does, stuns like Diana and can crit 800+ often (min hits are 200s). Did I forget to mention she also has a bleed like Natalia that pierces through defences and 205k HP? Gl lol. Only realistic way is T3 5* Yuri.