ENCOUNTER 1: THE BEASTS OF NORTHREND
The meta-achievement for the Coliseum raid lists the Beasts of Northrend as the first encounter of the dungeon. The monstrous menagerie is made up of three encounters total.
ACIDMAW AND DREADSCALE
Tirion Fordring: Steel yourselves, heroes, for the twin terrors: Acidmaw and Dreadscale! Enter the arena!
These are the "not one, but TWO jormungar" you've heard so much about. They come as a package deal. Sunwell raiders will undoubtedly call these guys the "Jormungar Twins". You'll see why below.
Each wyrm has their own set of abilities, but they're similar. Acidmaw has the following abilities, likely among others:
-- Deals 6938 to 8062 Nature damage to an enemy. Acidic Spew
-- Deals 3700 to 4300 Nature damage per 0.25 sec. to enemies in front of the caster. Paralytic Bite
-- Inflicts 11100 to 12900 Nature damage on an enemy and injects them with a paralytic toxin. Paralytic Spray
-- Sprays acid at an enemy and nearby targets, dealing 8325 to 9675 Nature damage and applying a debilitating paralytic toxin.
While Dreadscale has these:Burning Bite
-- Inflicts 12950 to 15050 Fire damage to an enemy and coats them with burning bile. Fire Spit
-- Deals 6938 to 8062 Fire damage to an enemy.Molten Spew
-- Deals 3700 to 4300 Fire damage per 0.25 sec. to enemies in front of the caster. Burning Spray
-- Sprays fluid at an enemy and nearby targets, dealing 8325 to 9675 Fire damage and coating them with burning bile.
Acidmaw's Paralytic Bite and Spray apply the following debuff:
Paralytic Toxin -- Applies a paralytic toxin that inflicts increasing Nature damage every 2 sec. and reduces movement speed over time until the victim is entirely paralyzed. (1 minute duration)
While Dreadscale's Burning Bite applies the following debuff:
Burning Bile -- Deals 4625 to 5375 Fire damage to allies within 10 yards. The burning bile of a jormungar is known to neutralize paralytic toxins.
From a cursory examination of the abilities, it appears that what'll happen is targets will get sprayed or bit by Acidmaw and have a paralytic toxin applied to them that will paralyze and kill them if left untreated. Thankfully, Dreadscale's bile can remove that toxin, so it'll be up to whoever's currently covered in Burning Bile to run up to those folks, clear them of their debuff with a Bile pulse, and then run the hell away until the bile dissipates (though I'm not really sure how long it lasts; the debuff for Bile doesn't currently have a duration in the spell files).
It's currently unknown if tanks can be targeted with the toxins. Oh, and:
Slime Pool -- A poison cloud appears which grows in area over 30 sec.
Because we loved those so much the first time.
The next beastie is:
GORMOK THE IMPALER
Tirion Fordring: Hailing from the deepest, darkest caverns of the Storm Peaks -- Gormok the Impaler! Battle on, heroes!
Gormok is a vicious magnataur with a number of snobold zealots in cages outside of the Coliseum. I actually have very little information on Gormok. The only things I can seem to find related to him, beyond this spell I assume is his namesake...
Impale -- Inflicts 125% of weapon damage to an enemy and causes it to bleed for 2625 to 3375 damage per application every 2 sec. for 40 sec.
...are a set of spells that indicate that Gormok's snobold posse will jump onto your back and annoy you during the fight. There's even an achievement for completing the fight with Snobolds alive.
Snobolled! -- You appear to have a snobold on your head.
The next spells in the book, which are stuns and interrupts, may belong to the snobolds as well, but I have no way of verifying that at this time.
The final monster in the menagerie is:
Tirion Fordring: The air itself freezes with the introduction of our next combatant -- Icehowl! Kill or be killed, champions!
The taunka hunter keeping Icehowl sedated indicates that Icehowl is quite literally the biggest and meanest of all Northrend's yetis -- and the northern variety are already orders of magnitude more brutal than the ones we see in places like Alterac. Not good news for you.
Icehowl has a number of abilities (not all indicated abilities may be his but the chances are very very good):
Sweep -- Whirls around, dealing 6938 to 8062 Physical damage to enemies within 15 yards and knocking them back.
Staggering Stomp -- Deals a staggering stomp that inflicts 7800 to 8200 Physical damage to all enemies within 15 yards and interrupts spellcasting for 8 seconds.
Arctic Breath -- An icy breath that freezes targets in a cone in front of the caster, inflicting 20000 Frost damage over 5 sec.
Ferocious Butt -- Delivers a ferocious headbutt to an enemy, inflicting 69375 to 80625 Physical damage and stunning for 2.5 sec.
Frothing Rage -- Increases Physical damage and attack speed by 50%.
Massive Crash -- Leaps into the air and crashes down with massive force, dealing 10000 Physical damage to all enemies, stunning them, and knocking them back.
There's really no other way to put this -- Icehowl is probably the most pissed-off and out-of-control boss I've ever seen, judging by his abilities. I really have no idea how you're supposed to fight him, with all of the knockbacks and silences and stuns, but I'm sure there's a method to his madness.