How did Vriska acsend to God Tier? I thought her dream self died

No, her dream self didn’t die. While Vriska was exploring her planet, Aradiabot showed up and beat the shit out of her then left. Tavros then brought her body to her Quest Cocoon. Her dream self was dying from the injuries her main body suffered so she mind controlled Tavros to write out her messages to him asking him to kill her main body quickly so she didn’t have to die slowly. Tavros was overwhelmed by the task and left in tears. She died via blood loss and her dream self then ascended.