Her mental sense is basically, seeing minds, like blips on a radar.  She can't read every mind in her radius, she has to pick and choose.<br/><br/>No, unless they are actually sneaking into the facility, it's Myriad's immunity to mental powers that will catch her attention. If Myriad gets within 250 feet of her, she'll notice.<br/><br/>And black hole or blank, either way it will be something outside Coral's experience.