Diadem finally happened… now a major question

On a fire Druid with 187MF no less. Now I raise the question of if my 99 sorc should be a fire sorc or self-wield infinity? (My infinity rolled low at -46%). I’m hoping for a Jah to make phoenix on this Druid and to use for a fire sorc, but would a nova sorc clear p8 and handle lightning immunes better? Experienced input please!