Shadowvoid (an evil stargate)

A shadowvoid is my idea on a wormhole device that works like a stargate. But it doesn't just take you to another planet, but the wormhole will also corrupt your mind and turn you into a whole new person. In this case, someone who is evil.

At the inner rim of the ring are a set of teeth to mimic a ring-shaped mouth that eats whoever passes through.

These shadowvoids are the evil counterparts to the stargates. Although, I haven't given much thought as to who created them. But I'll leave that up to your interpretation.