First of all, if you're running it for the 1st time, warn your members. It's not mandatory, but it helps. When someone announces it immediatly, for instance, I will gladly use my macros and try to make the run smoother.

1st floor : Trash mobs
3 adds will be in place when you arrive in the room. The MT will take them (I don't recommend you MT here, as the placement is very specific). OTs will take the adds as soon as they pop (immediatly after the 3 first adds are killed)
2nd floor : Boss (Angrya)
If you have no clue of his abilities, whatever your gear is or whatever experienced healers you have : you will die. So make sure you read a bit about it first. MT will tank in the middle of the room with the boss facing north. Whatever happens, do NOT move the boss at all. It will cast :

- "double vision", causing the ground to be blue/red. All players have to alternate the colors. 2 stacks of the same color : -2500 HP. 3 stacks : Instant death. If you move the boss, so do the colored parts on the ground. (and players will have to run and face a possible instant-death)
- Mortal Gaze : Immediatly inflicts doom to whoever is looking in his direction. To avoid the debuff, turn around. To get rid of it, in case you have been inflicted by the debuff, move to a glowing plateform. Of course as a MT, this is no good. As said earlier, you shouldn't be moving at all.
-Summoning of adds : Hourglasses need no tanking at all. They don't have any abilities. They just need to get destroyed fast by dps. The 2 adds that spawns in the middle need be OT'd as they appear.

3rd floor, Scylla , Xande and adds
Gates will be destroyed on both sides by the allies while the MT is on Scylla. The ones that haven't been killed will pop adds which need to be taken care of by the OTs. (Jormungand > Thor)
Xande will spawn soon after, along with other gates (same principle). Xande's earthquake can and should be silenced. (usually by Bards, but if a tank can do it, sure !)

4th floor : Boss 5 headed Dragon:
MT tanks it at the very top of the room, as close to the side as possible). OT can handle adds, but they don't really have to. They are so little dangerous that dps can handle them by themselves, and fast. The heads needn't be tanked either.
When jellies pop, make sure there is always one person standing in poison. That will avoid a much nastier jelly to spawn (inflicting silence to all players, making healing absolutely impossible)

5th floor : Adds. Tank the boss in the middle of the room. Grab that knight when it spawns (if you haven't been thrown away)

6th floor : Cerberus
A team will go for Adds, B goes for Belly (inside stomach), C goes for Chains.
The adds that need be grabbed by the A tank are, I heard, a bit difficult. I can't be sure of their english translations but they look like flowers/plants and inflict heavy damages on dps if you don't take them fast enough.
B team : will be the team to go inside Cerb's belly. To do so, attack a gastric juice (there again, not certain of the translation), they will make you mini. Then step onto the purple zone (vomit?) and you'll be eaten, litterally, by Cerb. Once inside, dps the stomach.
C tank : will handle Cerberus outside all along. Just try to make sure he is facing north. Chains will be probably taken care of by healers/ dps. No worries about that.

7th floor : Boss Cloud of Darkness
MT will suffer heavy damage. If you think you have too little for this, leave it to another. It's not rare to see MT and their healers ask for extra support from other healers. Or to switch MT in the middle of the fight (generally, due to death of the previous MT)

At some point, clouds will pop, and the boss will absorb them if they reach the boss. For every cloud reaching the boss, it gains one stack. By the end of the add wave, the boss will cast an attack proportionnal to the numbers of stacks he got. At 4 stacks +, some players will likely die. If there are more than 5, I recommend tank LB. That will avoid unecessary deaths. Other than that, it's mostly about dps.