Purged by Fire
The intention of this is to make hellfire a more fun and usable ability. The best use of hellfire is with a healer, so having it fit in a tank role makes sense. Instead of losing the unique aspect of the spell (self damage), I opted to make it easier to heal for healers by not having to cast purging spells and focus solely on healing. Other possible options to increase the value of the enchant would include making the channel un-interruptible, Lessening the damage taken (by 25% for example), or causing it to spread and refresh ignite ticks.