When casting multiple Fiend's on the same target, they interfere badly with each other.

1. Every Grip cancels simultaniously, whenever the first one ends or gets canceled
2. If a later cast Fiend's Grip cancels first, the first one, although no longer affecting the target, is not canceled and Ban channels nothing
3. Only the last cast Fiend's Grip drains mana, so that previous Banes do not gain mana

Current behavior: Multiple Fiend's Grip on one target share a debuff, causing each other to malfunction.

Expected behavior: Eachcast of Fiend's Grip places its own independent debuff.