Mimi choked a little as the scent of filthy, burning hair forced its way into her throat and nostrils. As horrible as it was, Mimi was thankful for the fireball and the disorganized nature of the rats. She stayed away from them as they burned and scurried, and in return she had been thus far unbitten. Alice continued to scream, and this would usually be a cue for Mimi to comfort her, but she didn't want to offend the girl again.
Thus, as she was safe for the moment and didn't know how to assist with fighting the rodents, she decided to start on the checkered wall. Her ability had not yet been honed, but she hoped that she could exert enough influence to allow her team mates access to whatever was beyond that wall.
"Widen the bottom middle gap in the wall," she commanded forcefully in the language of Mimics, pointing to the specified location. She had morphed her throat into her original form's so that she could make the sounds needed for the command, as no humanoid voice box could produce such noises.
What the rest of the party would hear was a horrid, guttural roar unlike that which any Human could articulate, like some terrible beast perpetually drowning in a sea of viscous slime. One who had extended experience with Mimics could tell that this sounded like the noises they would make, though nothing about its meaning could be distinguished. It was a noise that could drive sheer terror into lesser adventurers, and cause more common folk to swoon as terrible as it was.