Bob had asked me to share some of my experiences in ICC, so here goes!
Overall, I think that ICC 10 is close to the difficulty of ToGC 10. With the ready availability of Emblems of Triumph, this will change as the average gear level of the populance increases, but for now I think the comparison works. At least two of the boss fights so far depend on the raid being able to switch targets quickly and "get out of the fire", and that adds a level of complexity.
(I'm assuming that you have watched videos/read wowwiki, and so I will only mention things that I noticed as I was healing, or that are important.)
Trash:
- Marrowgar: The "big" thing here is the Bone Giants (or whatever they're actually called). These seem to be activated by traps of some kind on the floor. They tend to path around a bunch before engaging the raid, so you have some time to kill any other trash before you have to face them. They are non-tauntable, and have a nasty cleave, so be sure a tank gets to them first and points them away from the raid. They also have an unfair aoe stun that also interrupts/locks out casters. There really isn't any warning that the stun is coming, you just have to deal with it. You may be able to have your healers outrange or Line of Sight it, but I haven't tried. We wiped on that 6-pull when two giants activated and joined in the fun. I think you might have to do a pet pull on that room.
The other thing to note is the line of ice spikes that the undead casters use. This does about 12k damage to anyone standing on them, and so it important to get away from these, as topping off people damaged by these just adds more to the healers' already full plate.
- Lady Deathwhisper: There's a couple groups of cultists in the room before the Lady, and two High Priests. The cultists are nothing special, altho one of them drops a void zone when it dies, and sometimes seems to resurrect itself.
The High Priests have some kind of continual damage aura, as well as making a random raid member a "bomb". A challenge to heal, make sure your healers are prepared.
- Gunship Battle: Nothing really special about the trash here.
Marrowgar:
Lord Receptionist serves his purpose as gatekeeper well. He is a good raid check boss, making sure that you are prepared for the challenges ahead. Out of the four bosses, I think that he hits the tanks the hardest.
- It is important that the two tanks stay together at all times. We marked them up so that they could always find each other. A tank taking a full Saber Lash is going to die.
- This also means that you need to keep the two tanks alive. This fight requires strong healing, as both tanks are going to be taking a LOT of damage from Saber Lash. Healers are also going to get Bone Spiked, and you must prepare for this. If you run with 3 healers, this shouldn't be a problem, but if you run with only two healers, have one of your hybrid dps toss some healing on the tanks while the rest of the raid frees the Spiked healer.
- This fight is an endurance fight, not a dps race. As long as people are staying out of fires and switching to burn down Bone Spikes quickly, you should win.
Lady Deathwhisper:
Pretty easy fight. Just a few things to watch for:
- Viper Sting for the win. This will drain the Phase 1 shield quickly, and your Hunter will never run out of mana.
- Make sure you have a Frostbolt interrupting rotation set up for Phase 2. The Lady will cast these frequently and they do about 30000 damage. You don't want the tank taking these.
- During Phase 2, the Lady will summon tiny ghosts. They are pretty hard to see, but you can tell she's summoning one when she spits out a pink arc of energy to a random spot on the floor about 15 yards or so from her. The ghost will chase a random person and blow up for a lot of damage when they catch them. They can't be targeted, you just have to run away.
Gunship Battle:
This took us a few tries to get the pattern down, but once you do it's a snoozer.
- Make sure everyone gets a Rocket Pack from the Goblin next to Bronzebeard. The pack goes in your shirt slot.
- Divide the raid into two groups: a Bridge Crew, and an Away Team. Each group needs a Tank, DPS, and a healer.
- Two of the Bridge Crew dps takes the Cannons. Everyone else kills anything that comes over to your ship.
- When the enemy mage comes out and freezes your Cannons, the Away Team leaps over to the other ship. The tank keeps Saurfang busy (ours just used the rocket pack to leap around the enemy ship, keeping Saurfang chasing him the whole time), while the DPS burns the Mage down. Once the mage is dead, the Away Team returns to your ship. The key to this fight is minimizing the time your cannons are frozen.
- You don't want the Away Team to stay on the enemy ship too long, as Saurfang gains a stacking buff the longer you are on the enemy ship and will eventually start doing a LOT of damage to the Away Team tank.
- The Bridge Crew Gunners should focus on killing as many of the NPCs on the enemy ship as they can. This both reduces the damage that your ship is going to take, and makes sure the Away Team can focus entirely on the Mage.
Rinse, repeat, loot. Very easy fight once you get the rhythm down.
Saurfang:
The difficulty of this encounter depends entirely on your raid's ability to kill the Blood Beasts quickly, and doing so without taking damage from them. Saurfang doesn't hit the tanks hard (compared to Marrowgar), but he does do a lot of damage to the raid.
- Saurfang puts a curse on the tank called Rune of Blood. Whenever he hits this target, he will heal for a large amount, so unless you have very good dps, you will want to switch to a different tank until this curse wears off.
- Mark of the Champion persists through death, and so depending on how the fight is going, and the contribution that the dead player could be making, you may not want to resurrect them.
- As the fight goes on, Saurfang leeches more and more health from the raid making the last 15% of his health difficult to burn through. The amount of damage the raid is taking also increases as the fight goes on. For these reasons, I would recommend saving heroism (if you have it) to help burn through this last bit of health.