Playstyle & Rotation
The general Rotation for Destruction Warlock is pretty simple.
Immolate on the target at all times, make sure you can track this so you have 100% uptime
Havoc is your main 2 target cleave spell. You want to pretty much use this on cooldown whenever there are 2 targets up. Keep 1 stack of Conflagrate and have 3-4 Soul Shards ready for when you use Havoc.
Rain of Fire is your main AoE spell which does a lot of damage. Only use this if you know the mobs will not move, and you have 4+ targets. If you have Inferno talented, you want to use it with 2 or more targets, assuming they will not move, even during Havoc. But if there is a priority target, then you obviously would want to use Chaos Bolt during Havoc up to 3 targets.
- Pre-cast Incinerate when there are 3 seconds left on the pull timer.
- Cast Cataclysm (if specced into this) which will then apply Immolate on the target.
- Cast Conflagrate (so that it can start recharging).
- Summon Infernal.
- Use Dark Soul: Instability or any on-use trinket.
- During your opener if you’re ever about to cap shards then cast a Chaos Bolt.
- During your Summon Infernal uptime try and fit in as many Chaos Bolts in as possible whilst generating shards through Incinerate and spend your Conflagrate backdraft stacks on Chaos Bolt.
- Rain of Fire on 4 or more targets as long as the mobs don't move out of it. 3 or more if have Inferno talented.
- Keep Immolate maintained up to 6 targets, Cataclysm is great for doing this as it applies Immolate to all targets on impact.
- Havoc is worth using on fewer than 4 targets, as soon as there are 5 or 6+ targets you just want to be using Rain of Fire, however, you can still use Havoc to regenerate Soul Shards quicker to put out more Rain of Fires.