Church Of The Floating Fire
Do you need a place to slay all your party members? This is it. Do you need to crash your world with an unecessary amount of fire blocks? I got you. Summon your level 20 world-eater that has been asleep for the last 30000 years and is getting hangrier by the minute? Yup, go ahead.
With the church of the floating fire, you have a gothic style cathedral for your most bizarre sacrifices, executions and your occasional adoration of the Fire Lord. Make your players suffer to climb all the way to the top of the bell tower (note: bells are not included), and fight whatever hell spawn you may see fit (not necessarily in this order).
Warning: It may crash your ceiling limit, so be aware.