This is a World Boss encounter in a similar vein as Sporefall.  It launched with Patch 12.1 with a "World" difficulty (LFR).  With Season 2 arriving the following week, it also gained Normal, Heroic and Mythic versions.  Each of these are "flex" raids, with Normal and Heroic allowing a maximum of 30 players and Mythic allowing a maximum of 25.  It takes place in an instance reached underwater.

Tactics: 

• Bloodlust on pull.

• Pull the boss to the edge of the platform.  Raid stack behind the boss. 

• Several players will get blue arrow over them.  Run to the edge of the platform closest and drop a set of three frost orbs each.

  • Once they have dropped all three, they should pick one or two of them up, using mitigation/a defensive, before getting out of the puddle.

  • Off-tank picks up the rest, or other raid members.

• Tank: Water Jet frontal (Mythic only?) - use to clear frost puddles.  Taunt swap.

• Tank (Normal/Heroic): Iceblade Flurry - use defensive for the last two hits and then swap.

• Giant Alluring Bubble: Murlocs will start running towards it from the outside of the platform.

  • Can use CC/grips, etc.  Kill before they get to the bubble.

    • (Mythic: one large add that shields the rest .. kill this one first)

  • If any get through they turn into berserkers - pulse raid damage.  Kill asap.

• Water spouts around the edge of the platform with one gap.  Find the gap!