The moon-like Eye of Gith is the best example of something able to create a spatial rift. Those that live on this ancient transport use it to move back and forth between the Astral Sea and Nawirrûs's systems and worlds.
Many consider the the creation of spatial rifts to be dangerous, if not forbidden magic. This is because it is disruptive to arcane energies, sometimes nullifying magic items completely, their energy drawn out of them to power the rift. They also cause temporary damage to the Web, that if the weave spiders are near, the abusers stand to suffer quick death.