This pet was added briefly on the Patch 5.3.0 PTR but was removed just a few builds later. It was listed as reward from the Arena Tournament 2013.
In the same patch that removed Murkimus Tyrannicus, the source text for 
Murkimus the Gladiator was updated to suggest that Murkimus the Gladiator will continue to be the pet of choice for Arena Tournaments, such as the upcoming Arena Tournament 2013.
These barrels are located around the 
Battle on the High Seas scenario and restore 10% of your health per second while interacting with them.
When combined, you will receive the following item based on class and talent spec:
Death Knight - 
Insubordination Belt (Blood) or Insubordination Belt (Frost and Unholy)
Druid - Malcontent's Belt (Balance and Restoration) or Malcontent's Belt (Feral and Guardian)
Hunter - 
Tallgrass Guerilla's Belt
Mage - 
Dissident's Belt
Monk - 
Crimson Schism Cord (Brewmaster), Crimson Schism Cord (Mistweaver), or Crimson Schism Cord (Windwalker)
Paladin - 
Secessionist's Belt (Holy), Secessionist's Belt (Retribution), or Secessionist's Belt (Protection)
Priest - 
Reformationist's Belt
Rogue - 
Disowner's Belt
Shaman - 
Unbending Spirit Cord (Elemental and Restoration) or Unbending Spirit Cord (Enhancement)
Warrior - 
Insurrection Belt (Arms and Fury) or Insurrection Belt (Protection)
Warlock - 
Perjurious Belt
This is spell is cast when a player clicks on an object called "Strange Bowl of Dice" located in the cargo hold area of each ship in the scenario Battle on the High Seas. The result varies with the dice roll, which can be from 2 to 12 and appears to roughly follow the probabilities of rolling two six-sided dice. Unless you roll a 7, you will receive , a 15-minute debuff preventing you from using the dice again. As of the Patch 5.3.0 PTR, this debuff can be removed with any immunity effect (Divine Shield, Hand of Protection on yourself or others, Ice Block, etc).
Potential results:
2: 
Snake Eyes - You die.
3: 
Scurvy - You will die in 10 seconds unless you find a Barrel of Oranges and eat from it.
4: Ambush by ~8-10 Cursed Pirates with ~787k HP each - You will die unless you have your friends around to help or you are prepared for a fight.
5: 
Cannon Barrage - Cannon shots spawn all around you; RUN!
6: 
Black Mark - Cannon shots will land at your location every 10 seconds for five minutes.
7: Nothing - You may roll again with no cooldown.
8: 
Pirate's Boon - Your health quickly regenerates (4% per second).
9: 
Thick Skin - You gain a high level of damage reduction (25%).
10: 
Roll Cursed Dice - You gain a Cursed Pirate as a "guardian" ally.
11: Cursed Pirate Dice - You gain this ability as an 'extra action button' and can use it to throw dice at enemies.
12: 
Pirate's Life - You essentially gain a "second life".
The theme between the results becomes clear when displayed in this format. Rolls above 7 extend your life while rolls below 7 shorten your life. Additionally, the results get increasingly extreme as you approach the ends of the possible rolls
This debuff is placed on the player when the player rolls a 6 with the Cursed Pirate Dice in the Battle on the High Seas scenario.
This buff is given to the player when the player rolls a 9 with the Cursed Pirate Dice in the Battle on the High Seas scenario.
This buff is given to the player when the player rolls a 12 with the Cursed Pirate Dice in the Battle on the High Seas scenario.
This debuff is placed on the player when the player rolls a 5 with the Cursed Pirate Dice in the Battle on the High Seas scenario.
This debuff is given to the player when the player rolls a 3 with the Cursed Pirate Dice in the Battle on the High Seas scenario.
This buff is given to the player when the player rolls an 8 with the Cursed Pirate Dice in the Battle on the High Seas scenario.
