Megacyma, Mother of Tides

Trample, Hexproof, Indestructible
Kraken, Leviathan, Octopus, and Serpent spells
you cast cost {4} less to cast.
Whenever a Kraken, Leviathan, Octopus,
or Serpent you control deals combat damage to a player, draw a card.
Whenever Megacyma attacks, each opponent may
pay {x}, where {x} is the number of creatures they control. If they don't, return all creatures that
player controls to their owners hands.