Karazahn was my first true Raid, where I'd actually put in some forethought and prepared a specific toon to Raid with. Molten Core had been a complete mystery to me, where I'd let my online friends guide me basically by the hand in the preparation and eventually entering the Instance. After I'd levelled my first 70, a Warlock called Gronrad, I started down the path of Attunement that Blizzard had laid out before us.
Attunement
There was quite a long journey in order to obtain The Master's Key, the requirement for a Toon to enter Karazahn. It began simply enough, a couple of quests that made you kill and collect some items in the World. A bit of travelling here and there to different Quest Masters, nothing that was difficult for a single Toon to accomplish. This is where the solitary part ended, and the group content began.The next step required you to enter the 5-man Instance Shadow Labyrinth, and find the key fragment beside the last boss. When BC launched, entry into Shadow Labyrinth required a key, found at the end of another 5 man instance called Setthek Halls. Are you starting to see a pattern here? Much of BC required an Attunement in order to move forward in the game.
Heroic versions of each instance required you to purchase a key, a key that was only available for purchase by gold once you earned a certain reputation level with a particular faction. 5-man Instances were grouped into factions: Hellfire Instances required Honor Hold (Alliance) or Thrallmar (Horde) reputation. Entry into Blood Furnace would require Revered reputation before the key was made available to you. Every toon that entered those instances required that key. Auchindon Instances required Lower City rep, and so on. There were even specific instance keys, like Shadow Labyrinth and Shattered Halls which required you to either complete another instance first, or follow a particular quest chain in order to obtain the specific key. Fortunately, where a specific instance key was required, Blizzard thankfully required only one party member to open the door, the rest could enter as long as they had the reputation key for the Heroic mode. Rogues were in demand at that time, as they were able to pick the lock if they had the required lockpicking skill level. I used to park my Rogue at the entrance of different instances in order to pick the lock. As well, there were levers located inside the doors, in order to let people in once you were inside.
All of this eventually disappeared, or became easier, as Blizzard lowered the reputation requirements to Honored. At the beginning, however, it was much more complicated and time consuming. An Altoholic would have to send each of their Toons down the Attunement path in order to progress. For most people, having to do this chain a couple of times was enough. For me, I was happy to progress each of my Toons into Raiding, and ran those Attunement chains over and over. It wasn't only for myself, but there would always be someone else that needed a step in the chain, so finding people to run the instances with wasn't that difficult.
Entry into Karazahn
I was still with the guild called TWC when BC started, and was happy to find a spot on one of their 10 man Raid teams. Finally receiving my Master's Key after following all the Attunement steps, I was ready with potions and a bag full of Soul Shards. More memory lane tripping... Warlocks required Soul Shards to do most of their Warlocky things. Creating Summoning Stones, Healthstones, Soul Stones, you name it, it was required. So, you'd load up on Soul Shards in your specific Soul Shard bag, and considered yourself ready to Raid.We entered Karazahn and the Raid Leader started marking targets. One issue with CC in Kara... most of the mobs were Undead. Mages can't sheep undead, but Priests and Hunters had a heyday. This is where I truly learned the value of CC. 4 mobs beating on Raid-ready tanks during the first few runs of Kara were just too much to handle. Healers would fall behind, and a Tank would quickly fall to incoming damage. Add to that a Raid-wide fear that some of the mobs would insta-cast, it would turn into a wipe very, very quickly. Thankfully our Raid Leader was well prepared, and within a few minutes we were facting our first Burning Crusade Raid Boss, Attumen the Horseman.
We learned to position ourselves and target Attumen's mount first, so that the second phase would be brought about quickly. During the first phase, the mount would randomly charge the closest person out of melee range. I recall one particular very casual player who wanted to Raid. She was well liked by the guild, but just didn't have the Raid skills that would allow her to progress beyond anything more than a tag along in a Raid. The Raid Leader would have her position herself up front, in order to prevent the mount from charging and stunning any of the healers. She never complained about her role, in fact she seemed more than happy to provide a usefulness, in whatever capacity she could.
Moroes
We eventually progressed beyond Attumen the Horseman, and reached the Grand Dining Room, with Moroes and his band of mini-bosses. To this day, that is my favourite Raid boss of all time. Every time you faced Moroes, he would have 4 mini-bosses with him, each with their own ability. That was bad enough... but Blizzard added their own nasty twist in that there were 6 different mini-bosses that the 4 would be randomly chosen from. You never knew which 4 would appear, you had to adjust on the fly each time.One Tank would make the pull, and the Off-Tank would pick up one of the mini-bosses. The other 3 mini-bosses would be either Kited or CC'd. Priests would quickly shackle one, hunters would ice-trap a second, and usually the 3rd was kited by another DPS class. The DPS would then focus their fire onto the Off-Tank's mini-boss, trying to down that mob before the Off-Tank picked up another Mini-Boss. All during this, Moroes would disappear at times, re-appearing to apply a Gouge Damage-Over-Time (DOT) debuff on a random player in the Raid. Eventually, if all things went well, Healers would keep people alive while Tanks and DPS worked together to not only kill each Mob in turn, but to maintain their CC and Kiting until the Off-Tank could pick up each mob.
As a Warlock, most of my initial forays into Kara were just to output as much DPS onto the focused mobs as possible, while not breaking any CC, and using my abilities to help the Healers keep me alive. I'd marvel at the expertise some of our CC'ers had, one awesome Hunter in particular. I wish I could remember his Toon's name, but his real name was Matt. Matt was the first person I saw capable of not only maintaining a steady high DPS output on the targets, but at the same time he would keep one mini-boss ice-trapped, and ALSO kite another of the mini-bosses. This guy had it down pat, and I vowed to learn from him, as my next Toon to level 70 would surely be my hunter, Wylset.
The rest of Karazahn was pretty much the same excitement, divided into 2 nights of 3 hour Raiding. Eventually we'd clear it all in one shot, but at the beginning we were doing what every guild goes through, settling down the player rotations, getting people used to the fights, and picking up loot that would help us push through into the next encounter. We'd faced down the ever-changing Opera event, which rotated between a Romeo and Juliet fight, or the Wizard of Oz Council-type fight. We'd made it past the fun Chess event, and made it to the top of the castle to face Prince.
Each Raid Boss we faced had its own challenges and trials, sometimes it would take a couple of weeks to get the mechanics and placement down to a regular boss kill, sometimes it would be a straightforward one shot fight. At the beginning, we were churning through Raid members pretty quickly, rotating people in and out until we starting getting multiple 10-man groups running through.