Tunguska Event

 was an "impact" event, caused by an approximately 12-megaton explosion probable meteor air burst of small asteroid or comet on June 30, 1908 at 07:17 AM.

However, just after an asteroid landed, a portal named Parallelno opened up and, sometime later, some Sibiryaks civilians have summoned close to the portal.

External Link

 * Tunguska Event on Wikipedia