When a Wiccan radio host chooses to cast a spell to assist a desperate listener, things go horrifyingly wrong, as she unleashes something far more sinister and thus loses the listener in the process. Then she must find a way to get the listener back, the only way being an action that would put her own life in danger.

Another angle:
“A late-night Wiccan radio host sets out to rescue [a recently dumped] listener when her [retribution] spell unleashes something much more sinister.”

As a reader, the phrase “something far/much more sinister” is considered a teaser. Loglines are supposed to tell. Thus, I would rewrite to inject the sinister stakes to help the premise.

Make this yours, take care.

Hi grbrinkley,
This is how I personally see the story:

A Wiccan radio host who unleashes something sinister and loses one of her audience when she casts a spell to assist her must now get her back by putting her own life in danger.

I hope this helps.