The trick to this build is the combination of demonic sacrifice and shadowbolt. You rarely use rain of fire, so I prefer aftermath, but they're both filler points. The choice between aftermath and pyroclasm is up to you. If you want to really min/max, see what rank of improved healthstone the other warlocks in your raid have and pick whatever they don't have, so that you can have three different ranks of healthstone in a raid. For example improved healthstone, improved voidwalker, and aftermath. I'll focus therefore on shadow, and how to min max it.

Fire is also viable at low levels, but in my testing it always seems to fall just a bit behind shadow. The biggest downside to playing destruction is that it can be really boring if you go shadow. Destruction locks have no rotation to speak of so it's almost impossible to mess up and they are pretty durable for a caster. Demonology is more for PVP or leveling, and less viable in a PVE setting. At low gear levels affliction is very nice, and there's something to be said for having a token affliction lock just for the raid utility they offer. Simply put, destruction offers arguably the best damage in the game. Specifically, it's for destruction warlocks. Since there strangely seems to be a lack of class guides for 2.4.3 content, I thought I would make this one for warlocks.

Wow tbc 2.4.3 warlock specs