Demons.
As the door opened, Isaac entered another mysterious room. This time, it showed images of demons and what their arrival meant.
Isaac walked to the center of the room with thousands of bubbles hovering in the air. The videos showed destruction, families being ripped apart, the planet slowly getting plagued by black smoke and crimson skies.
After corrupting one planet, they would move to another and then to another. It lasted tens of thousands of years, till they didn't have anything else to conquer. Thus, they focused their attention on areas outside their planet's system. Thus, they became widely known as the Galaxy Conquering Demons.
They left behind a pile of bones, dead families, and plagued planets. The Demon Kings, when walking on the planet, would bring despair and calamity.
Isaac held his temples as all the pain, information, and loss of lives were sucked into his brain. It felt like someone was hitting his brain with a sledgehammer.