First up, will be Baron Ashbury who's currently a rather solid roadblock for PuG's because your success or failure is entirely dependent on your group's willingness to effectively interrupt. He currently has two abilities he will use in standard combat that should be interrupted as much as possible: Mend Rotten Flesh (gone in 4.0.6), a self heal for 10% that will lengthen the fight and has first priority, and Pain and Suffering, a Shadow DoT for significant damage that could - and should - be dispelled quickly if it does get off. Adding to this, Ashbury will also cast Wracking Pain on the party which adds a stacking 20% Shadow Damage buff and deals a base 10K damage to each member. This spell needs to be taken into consideration with the remaining two mechanics by the Healer.
Periodically, Ashbury will engage in what effectively amounts to a "Decimate" mechanic to those familiar with Naxx or the two puppies guarding the halls of the Plague Wing in ICC; casting Asphyxiate on the party and crushing the life out of you until you reach 1 HP. Luckily, he's going to follow this attack with a channeled ability called Stay of Execution that will heal you for up to 50% of your health but on heroic it also heals him for each tick. If you let this run too long, he can heal to full and you will never kill him so it's very important that he does not get more than 1/2 ticks of this before you interrupt it. That number can eventually be 0, but starting out should be weighed against how quickly your Healer can get you all back to at least 15 to 20K health in order to survive the next Wracking Pain when it's cast. Using self heals, if you've got them, coming out of that phase to help your healer won't hurt.
Now, the main reason you're going want to rein in his self heals and keep this fight as short as possible is because the stacking Shadow Damage buff from Wracking Pain will become a serious concern once you reach 20% health on Ashbury. At this point, he will adopt his Dark Archangel form and begin using Calamity on the entire party. This is a channelled Shadow AoE that deals ~5.5K/tick and essentially puts you into a burn phase in which you're either going to kill Ashbury or he's going to wipe you. Too many stacks of the Shadow Buff here, and the Healer is simply not going to be able to keep up for long, so get your interrupts down and manage his self healing to get here quick.
The second boss in here will be Baron Silverlaine and he's a pretty straightforward tank and spank. His first ability is to Summon Worgen Spirit's, which will be cast roughly 3 times a fight and periodically bring the ghosts of the old SFK bosses to fight at his side one by one. The Tank need merely pick these up and the DPS burn them down to keep things manageable. Secondly, he'll cast Cursed Veil which deals ~25K Shadow Damage and reduces healing taken by 75% for 8 seconds. As long as the Tank effectively picks up the spawned adds, he's the only target a Healer needs to prioritize removing this debuff from as there is otherwise no immediate damage that will come into play to take out DPS from lack of healing on this fight. So, Tank pick up adds, DPS burn everything down, Healer keep Tank up and debuff off him, and you'll be moving on in short order.
The third boss, Commander Springvale, is both the hardest boss in here to do "properly" and, luckily completely optional if he's giving you headaches or you're "too honourable" to cheese his mechanics; more on that in a bit. First, how you're "supposed" to do this fight.
Initially standing with one Tormented Officer and a Wailing Guardsman, the task for DPS is to burn these down and keep them from casting Unholy Empowerment on Springvale; this will heal him and grant him a charge of Unholy Power, more on that in a sec. These adds are Undead, so any forms of CC that will work on that type of mob can be used to keep them manageable if you're having problems burning them down. Once they're dead, move to DPS'ing the boss until he calls out "for aid", at which point you one of each type of add will enter the room again individually from the right and left hallway doors. Repeat your kill phase.
Now, Unholy Power, also generated by the primary special attack he will attack the Tank with so you can't eliminate it entirely, is used by Springvale to execute two specials; Word of Shame, a single target DoT that is persistent until death and takes 5% of the targets health every 3 seconds - keep the target up or lose them, and Shield of the Perfidious, a frontal half moon holy fire AoE that puts heavy weight on the Tank to keep Springvale pointed away from the party and everyone else to stay behind the boss. Complicating this in the tight confines of this room is that Springvale will periodically Desecrate and his doesn't just slow but also acts as a void zone so the Tank will need to move him out of it to stop taking damage and allow the Melee to work. It is during these adjustments where the reality of being in a tiny box, the tendency for Springvale to end up at odd angles, and that DPS needs to go where the adds are combines such that Shield of the Perfidious tends to end up doing much more collateral damage than it would otherwise.
The remaining two bosses are comparatively simple. Starting with Lord Walden, his primary mechanic is to channel three "mysterious mixtures" - you'll know he's starting this phase if you've cast bars on and you see him casting a ? to "choose" - each of which have different effects and, conveniently, colours when they're active. Toxic Coagulant is the "green" phase and causes him to cast a poison DoT on everyone in the room which does instant damage and then stacks to fatal levels of damage the longer you stay stationary. So, as long as it's green, you stay "moving"; circle strafing/jumping/whatever works best for you. Ice Shards is the "blue" phase and does frost damage in the room while adding additional damage to areas where the shards themselves land. Look for white dots on the ground and avoid them. Finally, Toxic Catalyst is the "red" phase during which a DoT will be applied to the party which will make all their attacks crit but will increase in damage the more you move. So, for this phase, stand still.
Wash, rinse, repeat a few times while staying spread as ranged/heals to avoid and/or dodge picking up the debuffs/damage from the Poison and Frost mixtures he will periodically throw at party members and this fight will be over shortly.
Finally, you will come to Lord Godfrey. This fight is currently a preposterously simple tank and spank as Godfrey does only three easily controllable attacks. Firstly, he will cast Cursed Bullet on random raid members, a curse that can be easily dispelled or healed through. Next, he will periodically Summon Bloodthirsty Ghouls that the tank will need to pick up and can be safely AoE'd down or held temporarily until Godfrey casts his final major attack: Pistol Barrage. This currently deals significant frontal cone damage and the Tank should step out of it to make life easier on the Healer. With sufficient healing on the Tank, you can also run the Ghouls through this to have Godfrey kill them for you and there's an achievement for doing so. In 4.0.6 this attack will begin targeting random players so it will become necessary for everyone to be more aware when it is cast or, though I can't test this yet, try to take advantage of things like standing atop the staircase to heal/cast/shoot from as ranged and heals to mitigate the attack if it still can not shoot "upwards", just in a direction on the current plane.
Other than that, he will also stack a healing debuff and DoT on the Tank but this will fall off during Pistol Barrage before stacking to unsafe levels. So, simply burn the sucker down and head on your merry way...