A short explanation of Mamizou's ability:
temp. Name: Four Little Tanuki
During Mamizou's attacks, all the youkai she summons are actually Tanuki in disguise.
This can be seen by the tails every of these youkai has.
Now, when Mamizou is hit during one of these attacks, the Tanuki will take the hit (not completely sure about this, but the damage seems to be negated) and is knocked out for a while.
This is represented by one of the leaves turning black.
When all four are taken out, they take a while to regenerate and Mamizou can not use her attacks for a while.
In most cases, the attacks are cancelled when she is hit.
However when she is hit during the preparation for her stone statue drop, the praying Mamizou will turn out to be a Tanuki and the real Mamizou will drop down on the enemy without delay.