Hallo! My name is Sunkist and I'm a Resto Druid playing on the US PvP Ner'Zhul server. I've played wow since about a month after release. I've dabbled with other classes but the druid will always be my class of choice.
Tonight the guild brought these pesky creatures down on 25man normal mode. I'd say the first phase was pretty easy, 2nd phase was the hardest, and the final phase was around the same difficulty as the first.
For those of you who are grid users like myself here is a list of the debuffs I added to show up as center icons for the fight.
Phase 1: Impale - tracks the DoTdebuff on the tanks Snobolled! - tracks who in the raid has a snobold vassal on their back
Phase 2: Burning Bile - tracks the fire debuff that does around 3-4k damage every 2 seconds and is the only way to remove the Paralytic Toxin from players Paralytic Toxin - tracks the poison debuff that slows the person then completely freezes them down and stops the person in their tracks. Also does damage.
Phase 3: No debuffs to track
Phase 1 Tactics: Have the range spread out if not simply to avoid the fires that are periodically shot onto random players. The melee takes a pretty big hit every once in a while but that's easily healed up before the next AoE attack on the melee. Most of the healing should be focused on the Tanks. At first on 25man we tried with 2 tanks but then found it easier to do with 3 tanks. Once a tank took 2 stacks of the impale debuff another tank would taunt it away. Make sure that all of the Range dps and even some quick melee dps have the following macroed and put onto their hotbar.
/tar snobold vassal
The boss also received a stacking buff that increased his damage by 20% per application. At first I thought this was due to too many snobolds being alive but now I think it has to do with either how long the fight has gone on or else how much HP the boss has left. Either way, we always got to 4 stacks or 80% increased damage and it wouldn't go any higher.
Phase 2: Definitely the most difficult part of the encounter. There are 2 giant worms that come out and one will be mobile while the other will be stationary. Every minute or so the worms switch so the mobile and stationary ones switch. Acidmaw is the worm that deals primarily nature/poison damage and most importantly casts a debuff called "Paralytic Toxin" which can only be removed by having someone with the complementary debuff "Burning Bile" to burn it off. Besides that the range needs to remember to spread out to avoid everybody receiving the debuff and the tanks need to remember to kite the mobile worm around since since it will periodically poop out a green cloud that looks similar to Grobbulus' poison clouds.
Phase 3: Pretty easy phase overall. The boss has 2 knockbacks. One is for people within 15 yards and it also interrupts the school of spells that was being cast during the time for 8 seconds (stay 15 yards away, duh). Then a big knockback that hits the entire raid, after which the boss will "charge" into one of the raid members and smash his head into the wall. After smashing his head the boss will do 1 of 2 things: enrage which must be tranqshotted by a hunter asap, or else knock himself out for ~15 seconds where he will take 100% more damage at the time. Another important ability of this boss is that he casts a frontal cone that is exactly like the freezing breath from the giants that are a part of Hodir trash. Just make sure your healers are spread out enough to cover this and it should be fine. One tip for the tank: have them move towards the center about 3-4 seconds before his "knockout" period because generally right after he comes to he'll whirlwind followed by a melee hit which K.O.ed quite a few of our tanks. But luckily the boss is tauntable so the tank can simply wait in position in the middle of the room and draw the boss to him that way.
All in all a pretty fun and not too challenging fight. I'm sure the heroic version will prove otherwise but I found it to be a rather enjoyable first encounter for the new 3.2 Colosseum.