Trueshot Aura

The Beasts of Northrend

First thing to notice here is how the encounter progresses. They no longer wait for you to finish, and are instead on a timer.
On 10man you get to deal with them if you’re a little slow
On 25man, if two “Phases” are up together, the encounter resets, so you NEED to finish on time.

The Jormungar will enter 2:30 after Gormak becomes attackable.
Mr. Smashy will enter 3:00 after the Jormungar become attackable.
The main thing to remember here is that you need all your dps to be pushing hard here.

Phase1 : Gormak
The main thing to notice here is the Fire Bomb. This is no longer just a flame patch. Every second it applies a debuff.
This debuff stacks up every second, and deals 2000 damage every 2 seconds for each application, and lasts for 20 seconds after you move out of the flame patch.
You will need to attack the snobolds here, even if you skipped them on nonheroic, as if you reach 4 snobolds he will be able to oneshot even a heroic-ulduar geared tank.

Phase2 : Jormungar
Acidmaw’s Poison debuff ticks a lot faster here, so fast movement is a higher requirement.
Nothing else you need to do differently here, just faster movement.

Phase3 : Icehowl
As per usual he does a knockback, and you need to run away. You no longer have a runspeed buff here.
If you can switch back fast, use Aspect of the Pack as soon as you start running to allow those around you to move a little faster.

Important: Tranq shot does NOT remove his enrage on heroic mode.