Nostalrius Begins - Quality wow vanilla realm (1.12)

Upon casting hellfire, the caster will try to resist taking fire damage. If you cast hellfire and resist the first tick, hellfire will continue to cast, but deal no damage to yourself, or to anyone else. It stops ticking entirely. As you have a higher fire resist rating, I can only imagine the spell becomes more and more useless as it's just a mana sink at that point.

Fixed.