If your dreamself die on a quest but your original body is still alive does the dreamself godtier ?And if so what happen to the original body ?

Until your original body dies, your Dreamself is not your ‘Main Body’, it only becomes your Main Body when you Ascend or when you die and get Kissed. As such, this copy by itself wouldn’t be able to Ascend in your stead. Now, if you died on the Quest Crypt with your Dreamself still alive, THAT’s an intriguing question. Would you ascend normally? Would your Dreamself just die while you Ascend? I heavily doubt you could have both a God Tier body AND a Dream Self active at the same time, that sounds like cheating the system.