The red and green Beasts in Otaria are quite recognizable, but what about the blue ones?
Artist Arnie Swekel was given the task of coming up with a concept sketch for such a monstrosity, and here's what he came up with:
The Creative team liked it so much, that they ended up using it on a card in Legions. The card is Riptide Mangler, and it also appears as the art on one of the Legions booster packs.
What does it do? You'll have to wait and see.
Also, look for an interview with Arnie Swekel by Toby Wachter coming up soon on MagicTheGathering.com.