Did a writeup mostly for my own use on the so far first and only boss of Baradin Hold, Argaloth and figured I might as well post it here as well in case it helps anyone. This will be for the 10 man version, don't know yet how things change if at all in 25.
Argaloth is a Pit Lord demon imprisoned in Baradin Hold.
Meteor Slash - 200k attack divided among anyone in front of him. Leaves a 100% increased fire damage debuff.
Consuming Darkness - Random targetted dot dealing ~8k per second over 15 seconds. Can and absolutely should be dispelled quickly.
Fel Firestorm - Cast at 66% and 33%, players will have to move constantly while he is casting to avoid fires landing at their feet.
Berserk - 5 minute enrage timer, increases his damage by 900% and attack speed by 150%.
Raid splits into two groups consisting of 1 tank, 1 healer, 3 dps which will be positioned at opposite sides of Argaloth during the fight. It is very important both groups pile up on top of their tanks to even out the Meteor Slash damage. No standing a bit outside to the side, it gets us all killed. :]
At 66% and 33% players leave their "groups" and spread out and keep moving while Fel Firestorm is being cast, but its important everyone gets back to their respective groups on their tanks immediately when its over. The Fel Firestorm is fairly short, but you can also watch Argaloth's cast bar to see how long is left before returning to positions.
Tank swap after each Meteor Slash to avoid the next one hitting players debuffed for extra fire damage. The absolutely easiest way to swap smoothly is to just watch for Argaloth's cast bar on Meteor Slash and switch right as it finishes. Be sure to be in position to resume tanking shortly before the Fel Firestorm ends. Use damage mitigation cooldowns agressively to help healers save mana!
The Consuming Darkness must be dispelled or it will burn healers dry very fast trying to heal it. Probably best to have a dedicated dispeller in addition to the two healers, as the fight is very taxing and mana intensive for healers as it is. If healer mana runs out too soon, 3 healers is an option especially while learning the fight, but it puts even higher dps requirements on the remaining 5 dps.
DPS'ers should use their cooldowns to increase damage early and often! with 6 DPS in the raid it is expected each one will do somewhere between 8-10k dps in order to get Argaloth down before Berserk. Healers will be very strained through the entire fight and they will love every little thing you can do to reduce incoming damage or light self healing. Don't expect a whole lot of healing during Fel Firestorm.