Legendary Hunter's Pet

Along with Legendary weapons, there could be one or more Legendary Beasts, which would have long, hard quest chains for hunters to tame.  These pets would be better than normal.  It could have multiple pet specific abilities, and a unique talent tree.  Perhaps a Hydra, or difficult to find dinosaur type, or a thunderbird type animal.  A good idea might be to have the animal in the Emerald Dream, and have to find or summon it there.  The quests and the like to get this beast tamed would rival that to get Atiesh, the Greatstaff, or any other Legendary weapon.