The Divine Teleporter is a teleporter that replaces the regular teleporter at the Temple of the Elders and all levels after it. There are two options at a divine teleporter. You have the option to "Loop" back through the previous levels and farm more items, or continue to the final level, Risk of Rain.
Looping back through levels creates new maps with more items and the time difficulty applied to them. Looped levels do NOT have to be the same layout or map. For example, if your beginning map was the Desolate Forest, looping on the Divine Teleporter in Temple of the Elders could teleport you to the Dried Lake. Looped stages will still be in order however, so you couldn't get Sky Meadow before Dried Lake.
For those confused by which key to press to activate which option, the "Use" key (default bound to "A" on keyboard) that activates teleporters will "Loop" players back to through the previous levels. The "Alternate Use" key which swaps On Use items (default bound to "Q" on keyboard) will activate the final level.