erucsbo
Explorer
Are you doing the 'black wave of neg energy' rolling though every 30 min? If the party is truly trapped that could make it rough. I had it rolling though and the party was convinced they were all going to die.
As time goes on I've started have it roll though a little quicker (25 min vs 20) with a little more damage and a little bit harder save DC. I'll keep raising it as time goes on.
I'm increasing it in intensity and frequency, but am making the waves still a day or two apart. 30 minutes apart doesn't give me much room to move and they still haven't gotten any keys or pulled any levers yet.