BLM Optimal Rotation Question - PrePot?

[Shamirah]

Never use DMG buff to cast your Thunder. Cause if you get Thundercloud proc it will deal damage but not put the DoT cause the previous one was stronger.

It was changed in 2.1. Now if you apply a weaker dot, it will just refresh the dot without the previous damage boost. You can try it by casting a ragingstrikes's boosted Thunder followed by a normal thunder.