Well as most of you know I spout out theorys like a maniac so I thought I would put them all in one thread to discuss!
Time to work this out!!
Step 1: Cut his Chain
Step 2: Throw him in the hole ( Whats the Significance of the hole?)
Step 3: Spell theories wrong!
Is it Kiskues version of defeating his hollow? The temporary way of keeping the hollow tame until the Vizard tought him to tame it a little more indefentaly? I still think Ichigo was able to call forth his hollow mask since he left Kisukes a shinigami.
It saved his life countless times in Soul Society arc, softening the blow from a lethal blow.
Ichigo unknowingly summoned his mask, just like he could after the Vizard training, I believe kisukes method is a little more temporary, and the hollow finally saw his opening, and took it.