The shield union purpose

Ten years ago, strange dimensional portals began to appear on the human continent. After examining the strange portals, it was discovered that they were dimensional distortions containing many dangerous monsters within them. In general, the public did not know what these portals were exactly, which spread terror and chaos on the human continent. But some of the few major powers knew that these portals were the dungeons mentioned in the legends, and they also knew what it meant for these dungeons to appear on the human continent because of that. A lot of the human superpowers decided to put together an international team strong enough to tackle the threats of dungeons and the unknown dangers outside the barrier. The team that would later be called the Shield Union.