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This battle pet/companion is found in the  "Tomb of the Forgotten." TCG set.  If you buy the epic collection box of this set the card is supposed to be guaranteed to be in there.  To obtain it you must go to the WoW Promotion page which gives you a redeemable in game code for Landro Longshot found in booty bay.  It is unfortunately the same model as the Zul'farrak dungeon beetle.  However the flavor text for the card "Easily mistaken for a common beetle, the sting of a sand scarab will quickly clear up the misconception should you be unlucky enough to be stung by one." makes it seem like these are some dangerous bugs. This companion can be caged and sold on the AH.  

This pet is obtained through the  "Throne of the Tides." TCG set.  To activate it you must enter the card serial on the wow promotion page which gives you an in game code to use with Landro Longshot in booty bay. When the creature is summoned it does a splash from the ground.  He is surrounded by a bubble of water that stays on him even when you're underwater.  Unfortunately it doesn't puff when poked.  This companion doesn't really have any special animations though it does have a large range of different subtle things.  The flavor text for this companion is "You might think this fish out of water would be a weak opponent... until you see the intensity that lies within its protective bubble."

This pet is from the  "Worldbreaker." TCG set.  This pet has the same model but different color than the Lil'XT from the blizzard store.  It does however maintain the same playfulness as stated by the cards flavor text "Always 'ready to play,' Landro's Lil' XT is almost indistinguishable from the original. Prone to tantrums and narcolepsy." as well as the destructive fun of destroying any other mechanical companion put out around him such as the toy train set or the mechanical gorilla.  This can be caged and sold in the AH.  To redeem the card you must first visit the wow promotion page and after you get your in game code go to Landro Longshot in booty bay. 

This battle pet is from the "War of the Elements." TCG set.  The code for it must be redeemed on WoW's Promotion page which gives you an in game code for "Landro Longshot" an npc in booty bay.  

This pet has a unique sound file for it's laugh when it kills an enemy in battle. It also has the ability to randomly ice block nearby critters and frostbolt them to death.  The card does unfortunatly share the same skin as the blizzard store lil'kt pet.

The flavor text on the card is "How the goblin Landro Longshot initially came into possession of the lichling remains a mystery, but he was all too eager to wager it in a game of cards."

This pet comes from the trading card set "War of the Ancients".  It does have the ability to be caged and sold.  Note it cannot be renamed to involve the name kilrogg as that name is reserved by blizzard.  The flavor text from the card states it's "Always watching, Always Judging".