About merging astral consciousness

[Charlie Olsen]

Hey guys! I'm new here, so if I insult anyone, I don't mean to.
I was reading on the JoS, and I found the page about merging astral consciousness... I haven't read it in a while because of lack of access but it mentioned shapeshifting. That implies that shapeshifting is possible... How? Could someone please explain this, I though shapeshifting was impossible?

Thanks!