BIG update, source: http://us.battle.net/wow/en/forum/to...?page=111#2202
Originally Posted by Blizzard EntertainmentGot a few updates for you guys. Standard disclaimer applies that this is all still in early testing and subject to change.
Fel Flame has gotten a slight rework. It now has a 1.5 second cast time, but can always be cast while moving. Also, it no longer extends the duration of damage over time effects (and, as such, no longer causes them to lose their "snapshotted" stats) and has gotten a small damage buff. The intent here is that you should be able to use this to keep up some damage when you need to move, but you'll want to stick to your standard rotation otherwise.
Looking specifically at Affliction, we're lowering the bonus damage that Malefic Grasp provides and moving that damage over into Haunt and the DoT effects themselves to compensate. We still want Malefic Grasp to be your primary filler for single target DPS, but this will make it a bit less punishing when you can't afford to channel it (especially in PvP). Haunt will once again be interrupted by movement, in favor of the Fel Flame change.
There's been a couple adjustments to the level 90 talents as well. Both Kil'Jaeden's Cunning and Mannoroth's Fury have had their cooldowns and durations lowered to 60 and 10 seconds, respectively. Mannoroth's Fury now only applies to the core AoE damage spells (Seed of Corruption, Hellfire, Immolation Aura, and Rain of Fire), but increases their damage by 100% while active in addition to the range increase. Note that Rain of Fire is being changed to no longer generate enough Burning Embers to be worth using in a single target rotation (so, Destruction shouldn't feel forced into Mannoroth's Fury).
These should hopefully be hitting the PTR in the next build. Once again, please remember that we're very early in the 5.4 development process. Any or all of this may still change before the patch goes live.