Stormtide Leviathan was the most powerful card in the first pre-con deck I ever bought, and 7 years later I'm still using it in one of my favorite decks. However, I wanted to make the absolute most out of this beast of a card, so I built this deck entirely around it. The most optimal play for this deck goes like this:
Turn 1: Play a Forest and Arbor Elf.
Turn 2: Play an Island or Hinterland Harbor, then tap it and and the forest you played last turn. Then, tap Arbor elf to untap your forest, only to tap it again to play Overgrowth to enchant your forest.
Turn 3: Play another Island. Now, you have 8 mana available on turn 3 - 6 green and 2 blue. You cannot summon Stormtide this turn, but you have lots of mana so you have multiple options. If you do not have another island in your hand, I recommend you play a Voyaging Satyr so that you can tap an Island twice next turn, guaranteeing a turn 4 Stormtide Leviathan summon. However, if you do have an Island in your hand to play on turn 4, you should take this turn to summon a Steel Hellkite, Sphinx of Uthuun, or the more advantageous Archetype of Imagination. Both Steel Hellkite and Sphinx of Uthuun are powerful flying creatures with powerful effects that can attack alongside Stormtide Leviathan if necessary, but casting Archetype of Imagination eliminates your opponents ability to attack entirely once Stormtide is on the field. Casting Archetype is your best option this turn. IF YOU HAVE NONE OF THESE 3 CARDS: The spells Opt, Serum Visions, and Foresee can help you draw out the cards you need quick and cheap.
Turn 4: If you have Stormtide Leviathan in your hand, cast it this turn. If you have Steel Hellkite or Sphinx of Uthuun out on the field, you can attack with them, but if you have an Archetype of Imagination out instead, it's best to just keep it safe.
Turn 5: Now, your engine is in full swing. With Stormtide out on the field, and hopefully an Archetype of Imagination, you should be able to swing Stormtide for an unblockable 8 each turn, as well as whatever powerful creatures with flying you have out. The only things you should need to worry about are spells that can destroy or incapacitate Stormtide or your flying creatures. If they should die, you have lots of mana, draw spells, and multiples of each creature, so you should be set pretty well.
Your sideboard also contains Counterspell if you would rather protect your creatures than have the option to draw them out if you do not open with them. The sideboard also Contains Brainstorm and Ponder, which are not legal for Modern, but are there to be switched with Opt and Serum Visions for casual play.
This deck is pretty powerful! It's got a really good early game engine that brings out powerful creatures very quickly, and can lock in a pretty quick win once Stormtide Leviathan is out. Overall, I think it's an excellently optimized deck that makes the most out of one of my favorite creatures.
