Undead Yahua and other Undead bosses take 10 lifes of my hero, but are hardly damaged by my troops. I use witches, archers, hammer soldiers and crossbows, all of them level 5. X Liu Bei is on level 15, with a Fire Fan and Flying Sand (all soldiers rend armor +20%)
As far as I remember I had no problem with them when I used taoist Priests. Are these bosses especially vulnerable to lighning, and immune to everything else?
These bosses only come in the arena.