百毒不侵吗蛇蝎心肠吗无坚
[băi dú bù qīn ma shé xiē xīn cháng ma wú jiān]
The user seems invulnerable and might possess tough-mindedness or even appear heartless at times ('百毒不侵' literally means not affected by a hundred toxins, indicating strength or invincibility against adversities; and '蛇蝎心肠' refers to someone with a cruel, vicious heart). It expresses the idea of being immune to harm but may also suggest a certain harshness.