Alright, since a few people I know, namely in my guild had trouble with obtaining this piece of the Cleric's epic. I though I would share my 2cp with everyone on how I got it :)
Me: 51 Non-battle Cleric of Innoruuk
Help: 62 Warlock (Necro)
First things first, HP/AC buffs are not really a necessity, seeing as the mobs you're going up are not higher than level 39. Since the mobs and placeholders are underwater, an Enduring Breath item is necessary (good for 27 minutes underwater). However, Dead Man(men) Floating is almost a blessing while doing this quest (good for 67 minutes underwater, and recastable underwater). We parked the Necro's pet right next to Deep (57-58 neutral mob underwater) and went topside, and waited. Not more than 45 minutes later, (after a few underwater checks and slaughterings of gobbies) Lord Bergurgle popped. He likes to run (swim) and unless you're a Froglok, you probably wont catch him. So remember to snare or root. It's definitely one of the easier parts of the epic. I guess all I'm trying to convey is that, having a Necro with you is by far the most beneficial class. As you won't have to go topside over and over to get air. Hope this helps ;)
Lariatha Imperlisia
51st Cleric of Innoruuk