A small guide mainly made to help out my guildies but almost anyone may read them.
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All hardmode bosses have more HP and all outgoing sources of damage are increased. For exact values, you may check wowwiki or something.
Lord Marrowgar
Differences from normal mode
- Bone spikes have more HP
- Bonestorm lasts 10s longer
- Lord Marrowgar continues to cast Bone Spike Graveyard during Bonestorm
Strategy:
- Spikes should be handled as per normal mode, with the entire raid stacking directly behind the boss so that they're easily reached. Make sure ALL DPS switches to dpsing the spike, especially the 3rd (set of) spikes just before bone storm.
- On Molten, a very effective way to avoid Bonestorm entirely, is have the two tanks juggle taunting Marrowgar when he casts Bone Storm to 'taunt' him back to them, thus the raid can stay in the same place indefinitely and reaching spikes easier
- Make sure RDPS are quick to switch to DPS the Bone Spikes that come out in the whirlwind phase, since melee will take time to run over.
- No one should be spreading out of the centre circle otherwise they'll get out of range of heals.
Lady Deathwhisper
Differences from normal mode
- HP increased (but not mana pool)
- Lady Deathwhisper is not tauntable
- Mind control on one person, like in 25man normal mode
Strategy
- Nothing much, just have CCs on the MC target and avoid ghosts at all times. MD/ToT to tanks, DPS should watch threat in P2.
Gunship Battle
Differences from normal mode
- Opposing ship HP increased
- Every time you wipe, opposing ship HP increases further (but I will chalk this up to Molten bugs)
- Knockback effect on the Rocketeer's attacks
Strategy
- Exactly the same as normal. Just avoid the Rocketeers' attacks if you're positioned on your side's ship else you get thrown off.
Deathbringer Saurfang
Differences from normal mode
- Blood Beasts have a enrage which increases damage by 300% (Scent of Blood)
- Blood Beasts have a 80% movement reduction aura which is active when they reach a certain distance from their target.(same thing, Scent of Blood)
- Saurfang regains 20% of his HP upon death of Marked target.
- Saurfang gains BP alot faster
Strategy
- Same strategy you normally use in normal mode.
Festergut
Differences from normal mode
-Prof Putricide casts Malleable Goo throughout the encounter (can target tanks/melee/ranged) This now also reduces melee attack speed, on top of increasing spell cast time.
Strategy
- Overall you basically use the same tactics as normal mode.
- Tank him in the middle. Have at least two healers and position them accordingly so no one is out of healing range. Position everyone at least 12 yards away from one another. RDPS/Healers spread apart, you have an entire chamber. MDPS should find the maximum possible range to attack Fester and try spreading apart from one another.
- Dodge the Malleable goo when you can. It doesn't kill you in one hit but it does high damage which can be fatal if your hp is below 70%. Plus, that spell casting speed/attack speed debuff is counterproductive.
- It is worthwhile to note that with the increased damage, any non-tank WILL get one shot by Pungent Blight if you have anything less than 3 stacks of Inoculated without any defensive cooldowns. (I am talking about the debuff you get from the spores.)
Rotface
Differences from normal mode
-Prof Putricide casts Vile Gas throughout the fight (The ability from Festergut that makes you Disoriented) but this interrupts you for a shorter period as compare to actual Vile Gas in Festergut.
- Mutated Injection gives a healing debuff that drastically reduces healing on the afflicted target, apart from its usual effects.
Strategy
- Ranged need to be spread out well to avoid chain Vile Gases. Slime spray still kills if you stand in it, so watch out for it.
- The whole raid needs to be aware of where the OT and big slime is at all times and immediately run near them if you have the slime's aggro. Watch out for the slime pool.
- With increased damage output from boss abilities, it is ever more important to keep away from Big Oozes and not stay near one for too long when merging your Small Ooze with it.
- Having three healers and maintaining their survivality is the safest choice of action. Rotface DOES NOT enrage so you can afford the sacrifice. Spam heals on people with the Mutated Injection debuff or they will die.
Professor Putricide
Differences from normal mode
- Gains new ability Unbound Plague: http://www.wowhead.com/?spell=70911.
It deals increased damage each second it ticks, you will have to throw it to someone else (throw as in, go close). Once it jumps off you, you get this: http://www.wowhead.com/?spell=73117 for one minute. The plague itself also disappears in one minute, but it will be recasted shortly after. The 250% debuff can stack if you get it on yourself more than once.
- Doesn't throw Tear Gas during transitions, but spawns a green and red slime simultaneously instead.
Strategy
- Unbound plague (though deadly) is easy to get rid of in Molten, just stand near the Abomination for a short amount of time and it will go away or have the Abomination come to you. Either case is fine.
- For transitions the raid should be stacked up at the green slime area to give the one targetted by the red slime time and space to kite it.
-Avoid Malleable Goo like plague or die.
- Important notes: Feign death, shadowmeld, ice block, HoP and Divine Shield have been proven to counter the Red Ooze.
Blood Princes
Differences from normal mode
- Gains new ability: http://www.wowhead.com/?spell=72999. Shadow Prison
This ability is a raid wide debuff, so anyone who moves will take damage. This includes knockback from vortexes and jumping.
- Kinetic Bombs drop faster
Strategy
- All abilities remain the same, probably with increased damage etc. The main issue will be Shadow Prison. It may take a few attempts to get the hang of it, but basically it forces you to move efficiently and not unnecessarily.
- To be clear - you take damage every second of movement, but not when you stop. For example if 1 stack does 500 damage and you move for 5 seconds you'll take -> 500 , 1000, 1500, 2000, 2500 = 7500 total damage, and damage ceases when you stop moving. However, if you move again before 10s is up (stacks haven't reset) you'll just add to it and take 3000 damage, for instance.
- A good practice is to have healers take the centre of the room (so that they can keep range with the raid + tanks) and everyone to find their own spot when Valanar is empowered to minimize damage from Vortex, and more importantly the knockback you take if you are near someone. (due to Shadow Prison)
Then when it's Taldaram, the ranged/healers should stack up and whoever gets targeted just runs back, so that it's only one person moving and taking damage from Shadow Prison.
Watch out for Shock vortexes too.. well all these are normal mode stuff.
Blood Queen Lanathel
Differences from normal mode
-Each vampire bite adds ~5% dmg to boss
Strategy
-No real difference from normal mode besides the increasing damage as more bites go out, which means your healers have to work harder. Saving survival raid cooldowns like Hymn/DiSac for the 2nd air phase would be good, since damage will be greater than 1st air phase.
Just execute the fight mechanics as per normal mode, and healers need to heal reactively very well (i.e. keep those with blood link at full HP, as they may get chain bloodbolted when they're together and moving away)
Valithia Dreamwalker
Differences from normal mode
- Dreamwalker's HP deteriorates over time
- Adds have new abilities: Lich's AOE Frostbolts have a Mana Burn effect, Abominations have frontal AOE, Zombies have a new debuff (? )
- Portals/Orbs are red in colour now, and they deal a stacking DoT for every stack you have. (i.e. more stacks, more damage)
-Orbs do not respawn like in normal mode.
Strategy
- 2 healers going into the portals would be a pretty comfortable setup to complete this encounter. You can also enter the same portal, it won't disappear like in normal mode.
- Maintaining your stacks of the buff is critical
-Very hard to get it done in first try but a convenient Molten bug makes Valithria easily doable in the second try with two healers in the portal.
-Also another molten bug is the DoT of the healing stacks, the damage doesn't do justice at all. Very negligible.
Sindragosa
Differences from normal mode
- Backlash acts as a splash AOE to those around you for 20 yards, not just damaging you alone.
-Frost Bombs one shots you... so hide well...
Strategy
- Those with Unchained Magic shouldn't cast at all, especially when a Blistering Cold is coming up
-Everyone must absolutely master hiding behind frozen tombs (or their shadow) since the frozen bombs Sindi throws is a nuclear bomb in disguise and it one-shots you.
The Lich King
- New ability Shadow Trap. Cast on player, and 5s later spawns a 10 yard black hole on the player's original location. Anyone touching it will be knocked off the platform. Cast in Phase 1 only.
- Phase 2 Val'kyr HP triples, however they drop their target at 50% health and fly above the raid and begin casting Siphon Life on the raid until they are killed.
- Phase 3 (last phase) Harvest Soul sucks the WHOLE RAID into the Frostmourne room. You have to kill Wicked Spirits inside (similar function as Vile Spirits, come downwards and blows up if it reaches you) as well as dodge falling bombs that rain from the sky.
Strategy
- (uh... none at the moment... I mean the way Harvest Soul is bugged in Molten... will add strats if we get past Phase 1 ^^)
So there you go, enjoy egg-heads :D