Tear of the Goddess Bugs

Tear of the Godess does not always add the "+4" mana as intended. In the description it states, "adds 4 mana on spell cast or Mana expenditure". When Karthus forst casts E, it does not add the mana as intended. With the new runes, manaflow band also does not allow for the +4 mana.

While this is a small thing, it is a bug none the less.

Please let me know if this was intended, or not. (:

Thank you