It’s time to give instant fellhunters back to demo locks. That one change would make the spec more viable.
And while we’re at it, give back the grimoire fellhunter interrupt thing. If it makes sense for any lock to summon a demon to interrupt a spell, it’s the demonologist. It’s pretty silly to let destro have the interrupt but not demo. Destro has the extra stun with the infernal. It’s not fun to be the only dps spec in the game without an interrupt. The fellgaurd stun does not lock a caster out of a school of magic like other interrupts.