Well of Many Worlds

Wondrous Item, Legendary

This fine black cloth, soft as silk, is folded up to the dimensions of a handkerchief. It unfolds into a circular sheet 6 feet in diameter.

You can take a Magic action to unfold the Well of Many Worlds and place it on a solid surface, whereupon it forms a two-way, 6-foot-diameter, circular portal to another world or plane of existence. Each time the item opens a portal, the GM decides where it leads. The portal remains open until a creature within 5 feet of it takes a Magic action to close it by taking hold of the edges of the cloth and folding it up.

Once the Well of Many Worlds has opened a portal, it can't do so again for 1d8 hours.