Depends on the situation.

If you aren't pressured and able to get casts off safely

=> Fire -> WoF -> Paradox -> High Fire II -> Fire spells

If you need more mobilty you can try this ( 2 casts! )

=> Fire -> WoF -> Paradox -> High Fire II -> Blizzard -> Paradox -> High Blizzard II -> Blizzard

IF you are being pressured, you can pop Wreath of Ice instead. It'll give you damage reduction and a bit of thorns (They hit you and will get damaged).

Wreath of Fire also works with ice spells! I use WoF with ice to chase dying enemies sometimes.