Thread:RubyRules!/@comment-27415795-20160108190557/@comment-4010415-20160108190850

Basically, Emerald's Semblance lets her make a person hallucinate, which means no one else can see what the person she's using her Semblance on is seeing.

So, yeah, she used her Semblance to make Amber hallucinate seeing a child in the road, and she used her Semblance to make Yang hallucinate Mercury attacking her.