Delphi Ardu IV is a planet that once served as an outpost of the Tkon Empire and was still guarded by Portal 63.
Delphi Ardu IV lies in the Delphi Ardu system and was once a remote outpost of the Tkon Empire, which disappeared about 600,000 years ago. In The Last Outpost, the Enterprise and a Ferengi vessel both lost power while passing the planet, and each crew at first blamed the other.
The drain came from an automated system left behind by the Tkon. Away teams from both ships beamed down to look for the cause and found Portal 63, a guardian who still watched over the outpost. After testing the two crews, the guardian ended the power drain and let the ships go.