Gravity Vortex

From DALpedia

The Gravity Vortex is essentially a portal but it's always set to one destination - a location beyond Gaian where stars are born. It was discovered that it is a zone of low pressure, and uses basic technology and incredibly advanced magic to make nearly pernament stable portals leading there, and encased them in round containers. The containers are made of a special material native to the mountain beneath the Nightshade's fortress. Using special techniques they balanced the forces of attraction between the particles that make it up, to make them a lot stronger inside than on the outside. However, the portals are not stable, so if large amounts of air pass through it, it collapses.