User blog comment:Xilinoc/Ch. 664 - The Gift/@comment-2211792-20160225174702

That's a mighty fine Stand Kisuke has got... oh wait, that's his bankai, isn't it? Who wants to bet Crimson Princess will have just the right abilities to counter Askin's Vollstandig? It's a guaranteed way to win.

I remember a theory that Urahara's bankai nullifies powers and makes them fail akin to Imagine Breaker (hence why it's unsuited for training), so why don't I go with that.