Precon Upgrade Guide
Deep Clue Sea Upgrade Guide
What to cut, what to add, and how to play the Bant Clues and card draw precon from Murders at Karlov Manor, commanded by Morska, Undersea Sleuth.
Murders at Karlov Manor
Deep Clue Sea
Clues into card draw: simple to pilot. Out of the box, before any upgrades. How we rate precons
Buy Deep Clue Sea on TCGplayer →Quick verdict
Deep Clue Sea is a card-draw deck that rewards you for drawing exactly two cards a turn, and its commander hands you the second one. Morska, Undersea Sleuth makes a Clue every upkeep and grows each time you draw your second card, so the plan is easy to follow from the first turn. The deck holds itself back with a slow mana base full of tapped lands, three expensive board wipes in a deck that wants to keep its own creatures, and a top end of seven-drops that don't use Clues.
TurnZero HQ rates Deep Clue Sea a 2 out of 5 on difficulty and a 3 out of 5 on power, as it comes in the box. That is our editorial read, not an official Wizards rating. The full hundred cards are on the Deep Clue Sea decklist page, and every other precon we cover is on the precon directory.
How the precon plays
Morska, Undersea Sleuth costs three mana and gives you no maximum hand size. At the beginning of your upkeep you investigate, which makes a Clue token you can sacrifice for {2} to draw a card. Whenever you draw your second card in a turn, Morska gets two +1/+1 counters. On your own turn, your draw step is the first card and cracking a Clue is the second, so Morska grows every turn as long as you have two spare mana.
Much of the deck triggers off that same second draw. Alandra, Sky Dreamer makes a 2/2 flying Drake, Jolrael, Mwonvuli Recluse makes a 2/2 Cat, Ethereal Investigator makes a 1/1 flier, and Detective of the Month makes a 2/2 Detective. A Clue held for an opponent's turn gives you a second draw there too, which triggers all of them again.
The rest of the deck makes and uses Clues. Tireless Tracker and Lonis, Cryptozoologist investigate on land drops and creatures entering, Erdwal Illuminator doubles your first investigate each turn, and Academy Manufactor turns every Clue into a Clue, a Food and a Treasure. Knowledge Is Power pumps your whole team by the number of cards you've drawn this turn for a big attack.
What works out of the box
Morska, Undersea Sleuth ↗
Makes a Clue every upkeep and gets two +1/+1 counters whenever you draw your second card in a turn, so it supplies its own trigger every turn.
Alandra, Sky Dreamer ↗
Makes a 2/2 flying Drake on your second draw each turn, including on opponents' turns, and pumps them on a big fifth-draw turn.
Tireless Tracker ↗
Investigates on every land drop and grows each time you crack a Clue. It keeps the Clue supply going without costing a card.
Erdwal Illuminator ↗
Two mana to double the first investigate each turn. With Morska out, that is two Clues every upkeep.
Academy Manufactor ↗
Every Clue you make also makes a Food and a Treasure. The Treasures pay for cracking the Clues.
Teferi's Ageless Insight ↗
Every draw outside your draw step becomes two, so each Clue you crack draws two cards and sets off second-draw triggers on its own.
What needs improvement
The mana base is slow for a three-color deck. Temples, bounce lands, Seaside Citadel , Krosan Verge , Path of Ancestry and three mono-color cycling lands all enter tapped, and Temple of the False God does nothing early. A deck that wants to spend two mana on a Clue every turn feels each tapped land more than most.
The removal leans on sweepers. Farewell , Fumigate and Organic Extinction all clear your own Drakes, Cats and Detectives along with everyone else's creatures, while the deck has only Swords to Plowshares , Aerial Extortionist and Confirm Suspicions for single threats. See how much removal a Commander deck needs for a target to build toward.
Upgrade ideas
Each upgrade below starts from something the deck does poorly and says what a replacement card has to do. The cards named are examples, not the only answer: if you own something else that does the same job, or a newer printing does it better, it goes in the same slot. Make one change at a time and play a few games between them, so you can tell which change helped. The general method is in how to upgrade a Commander precon →
1. Get the lands in untapped
Morska's engine wants two spare mana on every turn to crack a Clue. Every land that enters tapped either delays that or delays casting your next creature.
What to look for Dual lands in two of your three colors that usually enter untapped. Replace the mono-colored tapped lands first, since they fix nothing.
Cut, for example
Lonely Sandbar A tapped land that makes only blue. Cycling it costs a mana you'd rather spend on a Clue.
Secluded Steppe Same problem in white: a tapped mono-color land in a three-color deck.
Temple of the False God Makes no mana until you control five lands, so it is a dead draw in the early turns that matter most.
Add, for example
2. Trade a sweeper for targeted interaction
Three board wipes is a lot for a deck whose second-draw payoffs make creature tokens. Cheap answers to one threat let you deal with a problem without wiping out your own board.
What to look for Removal or counterspells costing three mana or less at instant speed. Answers that hit any permanent are worth more than creature-only ones.
Cut, for example
Organic Extinction Ten mana before improvise. Even with a pile of Clues and Treasures, it is very hard to cast on time.
Fumigate Destroys every creature, including your Drakes and Detectives. Farewell covers the rare game that needs a reset and can spare your artifacts.
Add, for example
Counterspell ↗
Two mana to counter any spell, and you can hold it up on an opponent's turn alongside a Clue.
Beast Within ↗
Destroys any permanent at instant speed for three mana. The 3/3 Beast it leaves is a small price for removing the real problem.
Path to Exile ↗
One mana to exile a creature at instant speed, so it pairs well with Swords to Plowshares.
3. Swap seven-drops for cheap Clue and draw pieces
The deck's payoffs care about the second card each turn, not about big creatures. Cheap cards that make Clues or draw on opponents' turns do more for Morska than a seven-mana body.
What to look for One- and two-mana creatures that investigate or draw extra cards, especially ones that draw on an opponent's turn so second-draw triggers happen there too.
Cut, for example
Tangletrove Kelp Seven mana for a creature that animates your Clues into 6/6s each combat. Strong when it lands, but it is the slowest card in a deck that wants to crack those Clues for cards.
Hornet Queen Seven mana for a wall of deathtouch fliers. It is good defense, but none of it touches Clues or card draw.
Add, for example
Thraben Inspector ↗
One mana for a creature and a Clue. It is the cheapest way to have a Clue ready for a second draw on turn two.
Faerie Mastermind ↗
A two-mana flash flier that draws you a card whenever an opponent draws their second card in a turn, which can set off your own second-draw triggers on their turn.
4. Keep Morska on the battlefield
Morska grows by two counters a turn and becomes the deck's biggest threat, so it draws removal quickly. Recasting it resets the counters and costs commander tax.
What to look for Cheap equipment or instants that give hexproof or indestructible to Morska or the whole board.
Cut, for example
Graf Mole Gains 3 life each time you crack a Clue and nothing else. Life is rarely what this deck is short of.
Magnifying Glass Three mana for a rock whose investigate costs another four. Morska and Tireless Tracker make Clues for free.
Add, for example
Win conditions
The deck wins with a wide board and a grown commander. Morska, Undersea Sleuth adds two counters a turn and can get big quickly, while Alandra, Sky Dreamer , Detective of the Month and Jolrael, Mwonvuli Recluse fill the board with tokens off the same draws. Knowledge Is Power turns a turn of cracked Clues into a large team pump, and Psychosis Crawler makes each opponent lose 1 life for every card you draw. The upgrades above mostly speed up the mana and keep your board alive long enough to get there.
Who should buy this precon
A friendly first Commander deck for someone who likes drawing cards. The one rule to remember is to crack a Clue each turn so you draw a second card, and almost everything else in the deck rewards doing exactly that. The extra choices come from deciding when to save a Clue for an opponent's turn, which you can learn as you play.
Checked against the printed decklist on October 10, 2026.
Track how the upgrades actually perform.
TurnZero HQ keeps a win rate per deck version, so you can change a few cards, play some games, and see the difference instead of guessing.
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