This boss only has one phase and is fairly challenging overall, being one of the more healing intensive fights.
About 20 seconds into the fight, the boss will spawn a pool of fire at the feet of the player and standing in it causes a light amount of fire damage. The location of this fire should be away from the either of the water pools on both sides of the room, else the fire will disappear quickly, which is not the aim of this fight.
Soon after the pool of fire spawns, the boss will then activate an iron construct, an add that deals moderate amount of damage. Additionally, whenever the boss activates a construct, he will gain a buff that increases his own damage by 20%, and this stacks for each iron construct alive. Due to this damage increase, as well as extra damage received from the iron constructs, it is imperative to kill the constructs as soon as possible. However these constructs have well over 3 million health so they can't be nuked down in a normal fashion. This is where the fire pool mentioned earlier comes into play.
Once an iron construct is kited onto the pool of fire, it will quickly gain a stacking buff. This buff stacks very quickly, capping out at 10 stacks, at which it becomes molten. While molten, the add will have increased haste, as well as dealing extra fire damage. As soon as the construct becomes molten, it must then be dragged into the water, where it will turn brittle, stunning it. Whilst brittle, any attack capable of dealing over 5k damage will shatter it, effectively killing the construct. It is advised to move away from the brittle construct before doing so as shattering can deal massive damage to anyone standing close. This process must be performed quickly as the boss does not wait very long before activating more constructs, and it should be repeated until the boss dies.
The handling of the constructs, as well as the amount of kiting involved, all the while keeping the boss dotted means a lot of damage intake with less room for healing. It is recommended to talent and glyph into those instant cast heals and use them whilst kiting the constructs. It is also worth mentioning that although the damage suffered during the fight is intensive, not a single hit taken (aside from boss crits) will trigger Masochism. Therefore mana is also very tight, and SW:D should be used whenever possible to conserve mana.