A Pond Portal is a portal which turns an area into a pond. This newly created alchemic pond, opens up in the center, revealing a massive wormhole to another world, also created by the pond portal manufacturer.
This portal was destroyed by David once he was done with it. Jane then returned to it, and recreated it for more evil purposes. It was supposedly destroyed after Jane and Mozart's brouhaha battle, but Mozart returned to it later, to communicate with his father's spirit emulation, this time, giving the world inside, no rules.
Mandy then owned it for awhile, when she modded the portal into Jane's front door, so that when Mozart ran from the exploding house, he'd land in the fourth wall.
Mandy later destroyed the portal and the fourth wall, absorbing the power to take over the world.