Why < 929MP in AF3? 929MP is the amount of MP required to cast a Fire > Blizzard III > Thunder, when transitioning into UI3 from AF3.
I do the same thing myself. Many people say go down to 500, but I don't go below 900-950 usually.


The calculations seem to also concur with the widely regarded opinion that hardcasting T2 is better than T3 during UI3, but the difference is so small, which makes it negligible.
However, the main factor to consider for the choice of Thunder is the DoT's duration. DoT clipping is a DPS loss, as reapplying a DoT does not add on to the current duration, but instead overlaps it with a new DoT, and any remaining ticks of Thunder DoT remaining before it is clipped basically equates to a DPS loss.
Thus, Thunder could be more ideal than Thunder III as it reduces the chances of clipping the DoT, moreso if you get a Thundercloud proc while the DoT is still on the target.
Interesting theory here. Have you done any parses on a dummy for Thunder II vs Thunder re apply?

More often than not, when you get a Thundercloud proc during AF3, your Thunder DoT from your previous hardcast would still be remaining on the target. As mentioned above, DoT clipping is a DPS loss.
An alternative solution is to hold the Thundercloud proc until you transition into UI3, effectively using it to replace the Thunder hardcast that you would be otherwise doing.
Although having a Thundercloud proc overwrite a previous proc without using it is also a DPS loss, but with only a 5% proc chance, the chances of this scenario happening would be pretty low.
However, it is also dependant on whether the 12 second buff would be able to last until you transition into UI3.
If you're not comfortable with doing this, then it'll probably be better for you to use Thundercloud procs as and when they proc. Or else, I believe this methodology provides at least some DPS increase as it reduces DoT clipping.
I believe while correct in the prefect scenario where no Thundercloud procs overwrite each other, would I'm on the fence to either play it safe and not hope for extra procs.

Sustained DPS vs Chance of Higher DPS