The Dark Opal is an extremely powerful machine designed by Mantid, and created by two Oracle Keys. It has laser beam generators in its eyes, mandibles that can fire large bursts of energy, and the ability to absorb the Oracle Key's power. It is the first Invectid battle machine that can be piloted. It was most likely destroyed in the explosion seen in "Welcome Back" when Buguese used it to ram into Fortress Mantid.
- Dark Opal is the last Invectid machine to be used in battle in the series.