User blog comment:AldenHeathcliffe/Chapter 551: The Burnt Offerings/@comment-10630156-20131003080937/@comment-10630156-20131007040241

Dangai train- The main problem = Reishi concentration

If they fight in Soul Society they will be helpless due to the insane amounts of Reishi there. The royal realm would be near impossible for a retreat to be taken to there because of the factors needed to get there. What is Tessai doing? maybe that underground area could be a viable option if it was modified a bit and Tessai could do this, Also last time we saw the visored Hachi was not with them, right? I'm expecting that to be something to do with the latter theory than a tea break or whatever the visored said he was missing for. With those two together that place could become a barracks in mere days which begs the question how long has Urahara been in Heuco Mundo?

It's the best place to fight the Wandenreich if somehow they could make it so that holes can't be blasted out of it.