Ravenous Passion + Bladefall of Trarthus

This relates to an interaction between Ravenous Passion and Bladefall of Trarthus. With Ravenous Passion equipped and Bladefall of Trarthus activated, the counter for Ravenous Passion's "Gain (7-10) Rage after Spending a total of 200 Mana" effect only increments if your mana actually decreases. If your mana regeneration is less than the per-second cost of Bladefall of Trarthus, then rage is gained every time your mana decreases by 200. If your mana regeneration is greater than the cost of Bladefall of Trarthus, then your mana never decreases and you never gain rage. Based on the wording of Ravenous Passion and the cost definition for Bladefall of Trarthus, this seems like a bug. I would expect the behavior to be that the cost of BF of Trarthus is always "spent" (if possible) and that regeneration restores what would have been the potentially lost mana. For example, if you had 4000 max mana, 200 mana regen per second, an unlinked BF of Trarthus, and no modifiers to mana cost, then every second the effect of Ravenous Passion would proc as 200 mana is spent by BF of Trarthus, but your mana would stay constant as the cost and regen would perfectly balance.

Currently, it seems that mana regeneration reduces the mana spent from BF of Trarthus, potentially to zero. Perhaps the current behavior is intended, but clarification would be appreciated. This issue likely also affects the Occultist passive Forbidden Power, however I have not tested that interaction.

Edit: It seems to be more complicated than just that your mana has to decrement by 200. Depending on use of clarity, Ravenous Passion can proc with a smaller mana decrease, however, mana has to decrease for rage-gain to occur.

From the description of Occultist's Forbidden Power on the wiki, it sounds like the charge gain only actually happens once per spell cast even if the mana cost is more than 400. Maybe Bladefall of Trarthus is only being counted as a single cast.