Create a group is dedicated to killing guardians and one to kill Ambushers
The raid has one minute to kill all the mobs. Create a group that is dedicated to killing guardians and one to kill Ambushers. Obviously melee damage dealers are initially on the guardians and ranged Cabal Online Alz damage dealers (hunters, mages, and warlocks) are mixed between the ambushers and the guardians.
After one minute, Lurker reappears and immediately does his Spout and Whirl combination. Once that is finished, repeat the first phase again. These two phases repeat until The Lurker Below is filleted.
At least two or three healers should be healing the main tank at all times. Other healers should help on the main tank during the first phase since the raid should not be taking that much damage. During the second phase, cross-heal as necessary, keeping an eye on each of the players tanking the adds. No pets except for warlock imps should be up for this fight. Priests and Shamans have the added ability to run across the water when he spouts to avoid damage. Mages are able to blink and can Ice-block to avoid taking Spout damage.
This is an easy fight once learned. The second phase is a little chaotic at first but becomes easier as the fight is learned. The most important part of this fight is the position of the main and off tanks. Make sure the off tank is building enough threat to be able to tank Lurker if the main tank is ever out of Lurkers melee range.