The text for Cube of Darkness says to remove all remain in place spells and end the magic phase on a 4+. Does this include your remain in place spells as well as your opponents?
Just remember it is only spells specifically listed as "Remains in play" and the CoD does not affect spells that last until the next magic phase. On a happier note however, vortex spells are RiP so the CoD will get rid of them if the 4+ roll is successful.