Mephota, Caller of the Deep

Islandwalk
Emerge {10}{u}{u}{u} (You may cast this spell by sacrificing a creature and paying its emerge cost reduced by that creature's converted mana cost.)
At the beginning of your end step, you may put a Kraken, Leviathan, Octopus, Squid, or Serpent creature card from your hand onto the battlefield tapped.