Oop'lajax
Drops from Scary Dark Chest. He's a little jumpy... especially around the face. Aquatic type. In you can find a with in it. Usually it'll be locked and you have to light all (?) nearby s in a short time frame (or some of them in the correct order?).
The 
Oop'lajax is a battle pet obtained from the Scary Dark Chest treasure in the Lost Mines area of The Ringing Deeps, introduced in The War Within expansion.
Guide awaiting review
Travel to The Ringing Deeps
Head to The Ringing Deeps zone and navigate to the Lost Mines area, where the Scary Dark Chest is located at 58.93, 30.26.
Unlock the Scary Dark Chest
The chest is normally locked and requires you to light all nearby candles to unlock it. If other players have recently completed the puzzle, the chest may already be open when you arrive at 58.9, 30.4.
Loot Oop'lajax from Chest
Open the Scary Dark Chest to loot Oop'lajax. Note that this chest is part of the Treasures of The Ringing Deeps achievement.
Tips
Oop'lajax will occasionally sit on your head and apply a debuff called Face Grab, with the flavor text 'Letting someone else do the thinking for you' — keep Oop'lajax summoned to experience this interaction.
