Leviathan, the Oceans

You must have have at least 6 blue devotion to play this card.
{u/b}{u/b}{u/b}, {t}: For each blue mana used for this effect, tap X permanents or creatures, where X is the amount of blue mana used. For each black mana used for this effect, send one of your opponent's creatures from the field to their hand.
Every time an opponent's card is tapped, Leviathan, the Oceans gains a +1/1 counter.