Frenzied Cannibalization increases both the amount of mana that can be harvested by your cannibalization ability as well as the amount of hit points consumed by the cannibalization.
you can find out in game on your own using this command: /alt list
/alt act 782 :)
Quote:
[Fri May 18 09:21:23 2007] Ability #782: Frenzied Cannibalization [Fri May 18 09:21:23 2007] Description: Frenzied Cannibalization increases both the amount of mana that can be harvested by your cannibalization ability as well as the amount of hit points consumed by the cannibalization. [Fri May 18 09:21:23 2007] Cost per Level: 5