While the dot effect itself is a double rainbow proc, this is *much* easier to do if you use tea with the queen and luck out with either indulgence of the mad queen (every spell procs a double rainbow effect. Always), joy of the queen with +10 to all stats and 50% chance to proc a double rainbow effect on a spell, or even +100PRR (so you don't die right away.
+100 PRR was used in both eh & ee DQ2 solo /afk runs, because nobody ever gets indulgence and I didn't get lucky with 50% procs either.
I wish I had a sorc to test it out sometimes!
Should be funny! XD
Maybe my FVS could do it anyway... just lesser spam since I've just 10 charge of magic missile :P