Deity creation / identification

[Jesse]

I don't know much about how these methods work, but what im curious about is why it is done in TB?

Is it to get a glimpse of shunyata? To see how sentient beings are created? Also when personifying a Buddha, do we in a sense become that Buddha?

I am also curious if it's possible for a diety/buddha to take form within your mind-stream, rather than simply just identifying as a diety/buddha?

Thanks in advance.