"I guess not every magical mirror can be a threat," Solstafir said with a noncommital shrug. He could read the draconic runes well enough, for all the sparse information that provided. Unless the inscribed words describe not just the function, but also the command to activate them. Seeing no harm in giving it a try, he looked at the mirror and spoke with careful and clear enunciation. "Show me." The power of dragonkind ran through his blood, the language as natural to him as the Dwarven tongue.

Spoiler
Show
If this does nothing I guess we can still go back to the octagonal chamber at the beginning and see if the other directions also unlock