Wait... did the island just move? Ramp up your mana while Arixmethes sleeps peacefully beneath the surface, then start dropping Krakens, Leviathans, and other horrifying things from the deep. Cast enough spells and eventually your innocent little island wakes up as a 12/12 sea monster ready to join the fun.
Commander
1x Arixmethes, Slumbering Isle
Creatures
1x Acidic Slime
1x Amphin Pathmage
1x Arcanis the Omnipotent
1x Breaching Leviathan
1x Burnished Hart
1x Charix, the Raging Isle
1x Chasm Skulker
1x Elvish Mystic
1x Fierce Empath
1x Fleet Swallower
1x Forgotten Ancient
1x Frost Lynx
1x Goreclaw, Terror of Qal Sisma
1x Inkwell Leviathan
1x Kiora, Sovereign of the Deep
1x Molimo, Maro-Sorcerer
1x Mulldrifter
1x Murkfiend Liege
1x Nezahal, Primal Tide
1x Nimbus Swimmer
1x Plated Seastrider
1x Reclamation Sage
1x Reef Worm
1x Reservoir Kraken
1x Sage Owl
1x Scourge of Fleets
1x Shipbreaker Kraken
1x Simic Sky Swallower
1x Slinn Voda, the Rising Deep
1x Stormtide Leviathan
1x Tromokratis
1x Wall of Frost
Artifacts
1x Arcane Signet
1x Bow of Nylea
1x Brawler's Plate
1x Helm of Awakening
1x Loxodon Warhammer
1x Simic Signet
1x Sol Ring
1x Swiftfoot Boots
Enchantments
1x Garruk's Uprising
1x Kiora Bests the Sea God
1x Primal Empathy
1x Wizard Class
Instants
1x Brainstorm
1x Cancel
1x Counterspell
1x Entish Restoration
1x Growth Spiral
1x Long-Term Plans
1x Naturalize
1x Negate
1x Opt
1x Return of the Wildspeaker
1x Telling Time
1x Titanic Growth
Sorceries
1x Cultivate
1x Explore
1x Farseek
1x Harmonize
1x Kodama's Reach
1x Rampant Growth
1x Rush of Knowledge
1x Shamanic Revelation
1x Whelming Wave
Lands
1x Command Tower
1x Coral Atoll
7x Forest
1x Halimar Depths
1x Hinterland Harbor
14x Island
1x Jungle Basin
1x Radiant Fountain
1x Reliquary Tower
1x Rimewood Falls
1x Simic Growth Chamber
1x Simic Guildgate
1x Temple of Mystery
1x Temple of the False God
1x Woodland Stream