From the info thread on official forums:
Question: How does Destruction’s Ember system work?
Answer: Basically, you build embers with some spells, and then spend those embers with Soul Fire, Ember Tap, or Fire and Brimstone.
Internally, this is how it works:
Immolate – DD + DoT on the target
Incinerate – generates 1/10th ember, or 2/10ths if it crits an immolated target.
Fel Flame – generates 1/10th ember, or 2/10ths if it crits an immolated target.
Conflagrate – triggers Backdraft and has a 12 second cooldown.
Soul Fire – consumes one ember instead of mana.
Fire and Brimstone – costs 1 ember and has no cooldown.
Ember Tap – costs 1 embers.
Each full ember costs 0.33% of your maximum health per second. If you stay below 1 ember, you take no damage.
And just 2 posts down from that:
Question: How does chaotic energy work?
Answer: We are experimenting with a resource-driven, rather than time-limited, caster model on the Destruction warlock.
In a nutshell, Destruction warlocks are not GCD locked. In fact, chain-casting spells as a Destruction warlock is less important than spending all of your resources.
Keep in mind this is all subject to change, but here is how Destruction flows at the moment:
• Start of Fight: Full mana bar, Empty Ember bar
1. Immolate the target
2. Conflagrate to trigger emberstorm
3. Incinerate to generate embers
4. Continue until you are low on mana
• Middle of Fight: Empty mana bar, ~2 Embers
1. Soul Fire
2. Soul Fire
3. Mana bar is mostly full (Soul Fire costs embers, so your mana refills during the Soul Fires)
In addition to increasing your base mana regen, Chaotic Energy increases mana regen even more with Haste. This means the ability to cast spells scales smoothly with gear.
As long as the warlock never lets her mana bar fill up and burn her embers, she's maximizing damage. This is very different from the standard caster model where priority is placed on casting at all times and ordering spells based on cooldown.
Our hope is that the Destruction Warlock will attract players who are interested in a playstyle that rewards spending resources at the right time, rather than constantly casting.
This all sounds extremely interesting, thoughts?