Helkom the Deep-Dweller

Shroud
Whenever a another nontoken Shark with power
4 or greater enters the battlefield under your
control, you may create a 5/5 blue Shark
creature token with your choice of vigilance or islandwalk. If you don't, draw a card.
"It's said they wait for us in the deep, growing in
number. In the end, they shall devour the world.