User blog comment:Twilight Despair 5/Abaddon as the Season 9 Big Bad?/@comment-82.34.210.166-20130419035817

The gates are sealed, but there was not mention of demon powers being bound in anyway. We know witches have some contact with demons. THey could be able to used that blood in the goblet communication thing. Demons have magics, so what stopping them casting magic in hell to affect earth.

We know that there is a door to purgatory in hell. Imagine if that news gets out, monsters/demons invading each others afterlife. While purgatory is locked up, we know there are routes and ways in and out. While each has their restrictions, any weakness in a barrier can be exploited.

The whole of season six was about how souls are power, what will happen when demons are trapped in hell yet with access to tens of thousands of souls. The thing is we dont know what sealing the gates of hell really means, the WOG is very metaphorical at times.