In Zul'Farrak, there are plenty of different types of mobs here, but mostly trolls. The scarabs will not attack you unless you attack them first. Since there are tons of groups of troll mobs here, it is always a great idea to have a Mage with you that can sheep some of them so that your group can wipe out the mobs faster. It is always a good idea to clear out all of the mobs on your way to the first boss for the experience and the loot. Once you have them all cleared out, you can move on to the first boss, Theka the Martyr.
When you get to the entrance to the corridor, there are a couple of groups of trolls that are on both sides. You will have to carefully pull these and have your Mage sheep them or another person sap them so that you can kill them off quickly. When they are gone, you can get up to Theka the Marytr. He is usually just roaming around and is really easy to take down. But, you have to make sure that no one uses any type of area of effect damage or crowd control tactics or it will aggro the scarabs around you as well. Now, when he's about to go down, he will suddenly become immune to melee damage and your tanks will no longer do any good. Here is where your casters will have to take him down the rest of the way. Once he's gone, make sure that everyone loots him since he drops the first tables of Mosh'aru.
When you are done with that boss, you can wipe out the scarabs that you need for that quest. It is the easiest to have someone do area of effect damage now to get them aggroed and out of the way quicker, instead of doing them one at a time. You do want to make sure that everyone gets the shells that they need before you move on.
After that, you will come upon Antu'sul. He really is not part of any quests, but he drops some great loot! Since he isn't part of a quest, you should only kill him if you have a strong group. Here is how you do it: you start to make your way up the path to his cave, but be careful that no one gets too close to the entrance or aggros him – and his aggro range is HUGE. You need to get close without aggroing him and then have your tank run in and get him. When you do, a big add of basilisks will spawn here while he's getting attacked, but they are easy to kill. Once this wave is dead, another one will come, which are elites and are a lot harder to kill. So, you need to have your off tank get one, have your Mage sheep one, and then clear out the others. When all of these elites are done, everyone can start on Antu'sul until he's down.
The next boss that you'll come to is Witch Doctor Zum'Rah. He's a bit harder, but not too bad. Now, you'll need to wipe out any patrols that you come across until you are where all of the graves are. DON'T OPEN THE GRAVES – this is a common mistake that a lot of new players make, and out pops an elite skeleton which is a bit hard to kill, and then the loot is poor. Make sure that everyone knows to leave the graves alone. Now, past the graves, you'll see Zum'Rah at his cauldron in front of you, but don't go after him first. There will be a patrol that will come around the next corner, so wipe them, then go after him. Here is what you do: have your tank run in again with everyone following. Have everyone go into the little room where he is. As he's attacked, he'll add several of the elite skeletons and you need to have people stay on Zum'Rah to get him down asap so that he won't keep spawning them. Then, once he's down, wipe the rest of the skeletons.
So – there you have the bosses. In the next part of this mini guide, we'll go through the strategy that is required for the best part of this instance – the steps!