Canyura, Newborn of the Sea

Canyura, Newborn of the Sea has indestructible
as long as you control three other crab creatures.
Whenever you put one or more shock counters
on one or more creatures, each opponent mills
two cards.
{g}{u}{u}: Draw a card, then put a shock counter
on X target creatures you don't control where X
is the converted mana cost of that card.