I never said the chance for Thunder Storm is higher or less than 5%, it's 5% for each cast of Thunder no matter the rank of it.

Also I never said refreshing Thunder during Umbral was a waste of mana. Did you even read my post or go into angsty teen mode to refute my point by stating a rotation with nothing backing it.

Your rotation during Umbral Phase is Blizzard III to start it, cast Thunder X and cast Fire III. Go back and read man.