A few months ago, I shared my love for water and built a Hydro vs. Pyro Duel Deck pair. Building a playable water-based deck was a challenge, as was dulling down enough a fire deck such that it could actually be a fun matchup. With Theros, Thassa, God of the Sea brings with her several more ocean-themed spells. Unfortunately, only Aqueous Form, Vaporkin, and the reprinted Griptide are great fits for the water deck (which had a strict theme of everything being water), but Master of Waves comes very close—he summons a lot of water, but he still has those darned fleshy bits.

The five Gods of Theros just happen to be legendary creatures, making them candidates to lead Commander decks all their own. While I don’t think I’d be able to build a tribal Gods deck (without a ton of Shapeshifters) or a pure water deck, building a deck around the God of the Sea does seem feasible. Thassa has four abilities; let’s take them in order.

Indestructible

While there are a few cards—such as Apocalypse, Warp World, and Harmonic Convergence—that can deal with a noncreature Thassa, she will mostly be untouchable as long as our devotion to blue isn’t high enough. The deck will, of course, want to reach five devotion in order to swing in with that sweet, sweet commander damage and have a big ’ol 5/5 for 3, but there are times when a Mutilate, Hallowed Burial, or the like will threaten our God despite her indestructible keyword.

Arcanis the Omnipotent – Arcanis provides three blue mana symbols toward Thassa’s devotion, which might make him a better candidate for the following category of cards, but remember that Thassa’s indestructible is for her protection, and it does no good against Terminus and similar effects. Thus, it will be important at times to bring our devotion to blue lower than five to protect her from such effects. Arcanis’s second ability, which returns him to our hand, can drastically drop our devotion at instant speed, protecting both him and our God from non-destruction-based mass removal.

Homarid Spawning Bed – While, again, providing good devotion, the Spawning Bed can allow us to reduce our devotion at instant speed. It is also good protection against opponents’ Confiscate effects, and we can even sacrifice Thassa if we need a few 1/1s instead of a 5/5—or if she’s about to be hit by Spin into Myth and we have no other creatures to sacrifice for reducing her devotion.

Seal of Removal – This Seal is an instant-speed bounce spell that increases our devotion, but like the previous cards, it can be used to reduce our devotion in a pinch or, sometimes, just to bounce Thassa outright.

Devotion to Blue

The only downside to Thassa being a creature is that she will become susceptible to some forms of removal. We tried to deal with that above, so for the most part, we will want a 5/5 commander around for attacking and blocking purposes. To this end, I’ve included a bunch of permanents—most of which are enchantments—that contain multiple blue mana symbols. Remember, though, that we may, at any time, want to reduce our devotion to protect Thassa, so it may not always be correct to flood the board with blue mana symbols.

Volition Reins, Steal Enchantment, Confiscate – Control Magic effects are among blue’s most powerful cards, and they do double-duty here. Once we’ve stolen an opponent’s permanent, our Aura will continue to exist on the battlefield, contributing to our blue devotion. And if the permanent we stole was blue, that will count, too.

Invoke Prejudice – This single card brings Thassa to creature status all on its own (in conjunction with Thassa’s own blue mana symbol), and it can have a very potent effect on the game. Nonblue players will be forced to pay double for their creatures, allowing us plenty of time to draw cards and find the right pieces to win the game. And without Thassa (or another of our creatures) on the table, even blue creatures from our opponents will cost double.

Land Equilibrium – Blue decks aren’t known for their huge numbers of lands on the battlefield. While we can hope to, with enough card-draw, play a land every turn, some players will have Explosive Vegetation, Into the Wilds, Oracle of Mul Daya, or the like, and this will force them to play by our rules.

At the Beginning of Your Upkeep, Scry 1

While a 3-mana indestructible enchantment that says, “At the beginning of your upkeep, scry 1,” probably isn’t as good as, say, Mirri's Guile, it isn’t terrible. Fortunately for us, Thassa has other abilities, too, but that doesn’t mean we can’t try, at least a little, to abuse the scry.

Soothsaying – This cheap enchantment is useful for many blue decks, and it synergizes even more with the Djinn than Thassa does. While scrying and soothsaying might seem redundant, it can be nice to put a card on top with Soothsaying and then scry it to the bottom of the library if it’s a card you just don’t want to draw.

Druidic Satchel – Like Djinn of Wishes, the Satchel becomes more exciting when we actually know what the top card of our library is. If we want an extra land, Thassa will help us narrow down whether that option is available. Druidic Satchel, I’ve found, is a quite potent card in almost any mono-colored, nongreen Commander deck.

Target Creature You Control Can’t Be Blocked This Turn

Thassa’s activated ability is a huge part of what makes her useful. Having a creature that can’t be blocked is quite potent, and in a format where 21 commander damage can kill a player, the fact that Thassa can grant herself the can’t-be-blocked ability is pretty exciting. Heliod, God of the Sun and Nylea, God of the Hunt grant other creatures vigilance or trample, greatly reducing their Commander utility. That’s not to say they’re terrible, but just that I’m really glad Thassa can target herself.

Ordeal of Thassa – Besides the name being so on-theme that it almost can’t be passed up, it also does a very interesting thing. Unopposed, Thassa deals 21 damage over three turns with the Ordeal—and, just for fun, at the end of it, we get to draw three cards. On her first swing with the Ordeal, she’ll become a 6/6; she’s a 7/7 on the following turn, and she’s an 8/8 the turn after that, for a total of 21 damage. Combined with her natural activated unblockable and indestructible superpowers, there’s not much the opponent can do.

Sword of Light and Shadow, Sword of Fire and Ice, Sword of Feast and Famine, Loxodon Warhammer – These Equipment all pump power by at least 2, bringing Thassa, God of the Sea right up to the magic 7, readying her for three-turn kills. Equally as important, these offer important abilities that mono-blue doesn’t have much access to: creature recursion, life-gain, removal, and massive mana acceleration.

Extra Combos

While deck-building around a theme of any kind is technically a Johnny activity regardless of the presence of combos, I just wouldn’t feel right not including at least a couple.

Riptide Replicator, Wanderwine Prophets – I mentioned Wanderwine Prophets above, but with Riptide Replicator, we won’t be limited by our Merfolk cards, and we’ll be able to take the rest of the turns of the game (with Thassa’s unblockable-granting ability). Note that I’ve included Strionic Resonator in the deck for its boundless utility and fun moments of discovery, but it doesn’t work great with the Prophets. While the saboteur trigger can be copied, it will still require the sacrifice of a second Merfolk.

Caged Sun, Fabricate, Ethereal Usher – Mono-blue is not great with mana acceleration, so Caged Sun is very important here. Other options are available, such as Gauntlet of Power and Extraplanar Lens, High Tide on an Isochron Scepter, or the usual gamut of artifact mana including Gilded Lotus. However, here, I’ve just included Fabricate and Ethereal Usher to tutor for the Caged Sun, as they are more versatile in their tutoring and leave a lot of spots for devotion cards.

Tidying Up

Of course, it takes a lot more cards to shore up a Commander deck. Take a look, have some fun, and watch your devotion.

"Commanding the Sea"

• Commander (0)

• Creatures (18)
• 1 Djinn of Wishes
• 1 Ethereal Usher
• 1 Fallowsage
• 1 Lone Revenant
• 1 Magus of the Future
• 1 Master of Waves
• 1 Raven Guild Master
• 1 Saprazzan Bailiff
• 1 Scroll Thief
• 1 Shipbreaker Kraken
• 1 Sphinx of Magosi
• 1 Stormtide Leviathan
• 1 Wanderwine Prophets
• 1 Arcanis the Omnipotent
• 1 Empress Galina
• 1 Lorthos, the Tidemaker
• 1 Myojin of Seeing Winds
• 1 Thada Adel, Acquisitor

• Spells (41)
• 1 Griptide
• 1 Curse of the Swine
• 1 Fabricate
• 1 Last Thoughts
• 1 Stolen Identity
• 1 Coastal Piracy
• 1 Confiscate
• 1 Cyclonic Rift
• 1 Dismiss into Dream
• 1 Dissipation Field
• 1 Flood
• 1 Frozen Aether
• 1 Future Sight
• 1 Homarid Spawning Bed
• 1 Invoke Prejudice
• 1 Land Equilibrium
• 1 Leyline of Anticipation
• 1 Lilting Refrain
• 1 Mystic Remora
• 1 Ordeal of Thassa
• 1 Propaganda
• 1 Recantation
• 1 Rhystic Study
• 1 Seal of Removal
• 1 Soothsaying
• 1 Steal Enchantment
• 1 Thought Reflection
• 1 Treasure Trove
• 1 Volition Reins
• 1 Caged Sun
• 1 Crystal Chimes
• 1 Druidic Satchel
• 1 Loxodon Warhammer
• 1 Riptide Replicator
• 1 Scepter of Insight
• 1 Strionic Resonator
• 1 Sword of Feast and Famine
• 1 Sword of Fire and Ice
• 1 Sword of Light and Shadow
• 1 Trading Post
• 1 Bident of Thassa

• Lands (40)
• 32 Island
• 1 Halimar Depths
• 1 Mystifying Maze
• 1 Reliquary Tower
• 1 Temple of the False God
• 1 Terrain Generator
• 1 Thawing Glaciers
• 1 Academy Ruins
• 1 Minamo, School at Water's Edge

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Andrew Wilon

@Silent7Seven

fissionessence at hotmail dot com