Board Thread:Theories and Speculation/@comment-32891032-20170929184505/@comment-734582-20170929201225

Wood release is just water+Earth. It seems that having a strong vitality can make it stronger, but it's not a necessity.

It seems to me that Yin and Yang release are just nature transforms. Just as the elemental releases force chakra to mimic an element, yin and yang release force chakra to mimic their respective sources.

In the case of Yin release, it mimics "imagination". That is, it can freely take shape but has little substance. See: Mind transfer, shadowbindings, genjutsu. Note that as Itachi said, one person's reality is another's fantasy, hence the connection to spacetime (reality) and genjutsu (fantasy) as is often seen.