Anyone who raided in ICC knows that any kind of alchemy/do-it-your-self-kitchen in the back of the room spells trouble for your raid. At some point the boss is going to throw something together and it's going to hurt. Maloriak is no exception.
As in normal mode you will rotate through red/blue and a green vial phase. The same strategy applies to them in heroic as it did in normal. Stack up during the red phase (unless you have have Consuming Flames on you) and pop your damage cooldowns. Spread out in blue phase (just in melee ranged, don't make the mistake of running away). If you are the designated interrupted for either Arcane Storm or Release Aberrations, or the designated purger for Remedy, be on your game. Especially if you're on Release Aberrations, make sure you tell your tanks what order you're letting them out in, or ask them what they prefer. We usually kicked the first cast and let the next three go.
What heroic mode brings to the table is black phase. Maloriak will always start with a black phase and then cycle through the others. Thus black -> red/blue -> green -> black -> so on.
Vile Swill and the add tank will pick them up and kite them around the back of the room (usually along the walls from left to right). These adds must be AOE'd down. "Oh crap," you say, "not AOE damage. It takes forever to get flame shock rolling on 3 of them." Well, just be thankful, my young shamans, that you are doing this after the patch. At least now fire nova will refresh the shocks a bit. Get your flameshocks up - you'll need to be tabbing a lot anyway to avoid pulling threat off since it will be low from tank kiting - and drop magma totem constantly as you move.Use maelstrom stacks to throw a chain lightning off. The chaos that is our AOE dps only gets worse when you consider you have to be constantly dodging Dark Sludge pools which are sprayed by the blobs. This fight, more than any other, really makes me which we had some sort of cleave or fan of knives type attack. A whirlwind perhaps? We do need more wind based spells...
And no, you cannot just single target dps any of the swills because you *will* pull off the tank and die a horrible death.
After black phase is over take a moment to wonder why you've just pressed 8 bajillion buttons and your aoe dps does not seem to reflect all that effort, then move on with the normal phases.
There is the option of switching to a spellpower (flametongue enchant) main-hand and just standing with the ranged while keeping up a fire nova/chain lightning rotation. I happen to refuse to do this because if I wanted to use spellpower weapons I'd roll elemental. However, for this fight especially, your dps would benefit some and so if you feel so inclined, go for it. Remember to switch back after black phase is over. .
A note on managing adds during the normal phases: our dps got to the point where it was high enough that we had times where we had to stop on Maloriak or risk pushing him into phase 2 early, so we would let the first 3 casts go and kick the last, giving the ranged time to focus the adds for a bit of pre-green phase nuking.
Remember to dodge the falling ice in Phase 2 and you'll be all set. Happy Raiding!