If your Bench is full, it deals 120 damage, which isnt impressive compared to other ex Pokemon
It has decent stats, and a 2/2 every turn is pretty darn good for two mana
While Manabarbs can be effective in certain situations, there are other more efficient cards like Price of Progress or Eidolon of the Great Revel that can deal more damage consistently
Meanwhile, Krothuss, Lord of the Deep can copy your nonlegendary octopuses to triple up on value (since it gives you two tokens of copied KLOS sea creatures)
It's got a big ol'booty and it wants to throw artifacts at people's faces in order to take them (or their things) down
In my initial prototype for the White Auracite, I explored effects that would recreate the story as faithfully as possible