User blog comment:Master Ceadeus 27/The Artisan's Arena 2 - Yuki vs Relcia/@comment-5020152-20140828000943/@comment-5448890-20140831191758

Dark, I repeat, do /not/ take control of other characters. Any ability that would do that without utilizing a recoverable weakness in the character that it is attempting to control is /not/ allowed.

Invading a weak body after a weakening or darkly magical attack leaving their spirit: OK!

Invading an otherwise perfectly strong, healthy body just by fusing it or otherwise: NOT OK! This will prevent overpowered characters as well as dominion.