Precon Upgrade Guide
Sliver Swarm Upgrade Guide
What to cut, what to add, and how to play the five-color Sliver precon from Commander Masters, commanded by Sliver Gravemother.
Commander Masters
Sliver Swarm
Every Sliver buffs the rest, the deck most people bought the set for. Out of the box, before any upgrades. How we rate precons
Buy Sliver Swarm on TCGplayer →Quick verdict
Sliver Swarm is one of the stronger decks in Commander Masters because Slivers share every ability with each other, so a board of five of them is far more than five creatures. Sliver Gravemother gives every Sliver in your graveyard encore, which means a board wipe turns your graveyard into a second army. The places to improve are a five-color mana base that enters tapped far too often, two board wipes and a removal spell that are awkward in this deck, and a few of the older, weaker Slivers.
TurnZero HQ rates Sliver Swarm a 2 out of 5 on difficulty and a 4 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 Sliver Swarm decklist page, and every other precon we cover is on the precon directory.
How the precon plays
Sliver Gravemother is a five-mana 6/6 with two effects. The legend rule doesn't apply to Slivers you control, so you can keep multiple copies of legendary Slivers like Sliver Hivelord . Each Sliver creature card in your graveyard also has encore equal to its mana value. Encore exiles the card and creates one token copy for each opponent, each attacking a different opponent with haste, and they are sacrificed at the next end step.
Encore matters most on the Slivers that grant abilities. In a four-player game, three temporary copies of Megantic Sliver give every Sliver +9/+9 for the turn, and copies of Bonescythe Sliver or Cloudshredder Sliver give the team double strike or flying and haste. A dead lord is still a threat as long as it is in your graveyard.
The early game is about getting the right Slivers down. Gemhide Sliver and Manaweft Sliver turn every Sliver into a mana source, Hatchery Sliver lets you pay a Sliver's cost again to make a token copy, and Herald's Horn , Vanquisher's Banner and Icon of Ancestry cut costs, draw cards and pump the team.
What works out of the box
Sliver Gravemother ↗
Gives every Sliver in your graveyard encore, so a board wipe only delays the attack. Encored lords stack their bonuses for one big turn.
Sliver Hivelord ↗
All your Slivers have indestructible. It shrugs off destroy-based board wipes and most combat.
Manaweft Sliver ↗
Every Sliver you control taps for any color, which fixes the five-color mana and ramps at the same time.
Hatchery Sliver ↗
Gives each Sliver spell replicate equal to its mana cost, so late in the game one card can become two or three Slivers.
Megantic Sliver ↗
Slivers you control get +3/+3. Encored from the graveyard, each opponent's copy adds another +3/+3 for the turn.
Cloudshredder Sliver ↗
Two mana for flying and haste on every Sliver you control, which turns a new board into an attack the same turn.
What needs improvement
The mana base is the biggest problem. Eight tri-lands, three cycling duals and four sacrifice lands like Flood Plain all enter tapped, so many games start with two or three turns of doing less than the deck could. A five-color creature deck needs to cast a two-drop on turn two.
Some of the interaction doesn't suit the deck. Cleansing Nova destroys all of your Slivers unless Sliver Hivelord is out, or all of your own artifacts and enchantments on the other mode, and Decimate can't be cast at all unless there is a legal artifact, creature, enchantment and land to target. The deck has very little cheap, instant-speed removal.
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. Fix the five-color mana
Every land that enters tapped delays the Slivers that make the deck work. Lands that make any color untapped fix both problems at once.
What to look for Lands that enter untapped and make any color, or that make any color for Sliver spells specifically.
Cut, for example
Flood Plain Enters tapped and then has to be sacrificed to fetch a Plains or Island. It costs tempo for a single colored source.
Rocky Tar Pit The same slow fetch for a Swamp or Mountain. The deck has enough tapped lands already.
Mountain Valley Another tapped land that sacrifices itself for a Mountain or Forest.
Add, for example
Sliver Hive ↗
Taps for any color to cast a Sliver spell, and late in the game it makes a 1/1 Sliver token for five mana.
Mana Confluence ↗
Enters untapped and taps for any color for 1 life. It casts any card in the deck on turn two.
City of Brass ↗
Another untapped land that makes any color, dealing 1 damage to you each time it taps.
2. Swap clunky removal for cheap instants
The deck's interaction includes a wipe that kills its own board and a sorcery that often can't be cast. Cheap instants answer threats without slowing the Sliver plan.
What to look for Instant-speed removal costing three mana or less that hits creatures or any nonland permanent.
Cut, for example
Cleansing Nova Destroys all creatures, including your Slivers unless Sliver Hivelord is out. The other mode hits your own artifacts.
Decimate Needs a legal artifact, creature, enchantment and land target to be cast, which often means hitting one of your own permanents.
Add, for example
3. Replace weak lords with stronger Sliver payoffs
Some of the older Slivers give small bonuses that a better card does more efficiently. Every slot that becomes a strong Sliver also improves the encore turn.
What to look for Slivers that grant a large bonus to the whole team or that put extra Slivers onto the battlefield.
Cut, for example
Blade Sliver Gives every Sliver +1/+0, the smallest bonus in the deck, and it applies to opponents' Slivers too.
Clot Sliver Lets Slivers regenerate for two mana each. Sliver Hivelord already makes the team indestructible.
Add, for example
The First Sliver ↗
Has cascade and gives every Sliver spell you cast cascade, so each Sliver you cast brings a cheaper free spell with it.
Sliver Legion ↗
Each Sliver gets +1/+1 for every other Sliver on the battlefield. With encore copies out, that bonus gets very large.
Muscle Sliver ↗
Two mana for +1/+1 on every Sliver. A cheap lord that makes the whole team bigger from turn two.
4. Draw cards from Slivers entering
Slivers want to keep coming. Two of the deck's draw cards are symmetrical or cost an attacker, and a typal draw engine is a straight upgrade.
What to look for Permanents that draw a card when a creature of a chosen type enters or attacks, or when a creature with a new name enters.
Cut, for example
Windfall Every player discards their hand and draws new cards. It refills opponents as much as you.
Hollowhead Sliver Gives Slivers a loot ability that taps them, which costs you attackers and doesn't add cards.
Win conditions
The upgraded deck wins by getting four or five Slivers out early, giving them flying, haste and size, and attacking. If a board wipe resets the game, Sliver Gravemother 's encore brings back the lords from your graveyard as hasty copies for one large attack, and Sliver Legion or Megantic Sliver copies push that attack to lethal. Kindred Discovery keeps your hand full between waves.
Who should buy this precon
A good pick for a newer player who wants a strong deck with a clear plan. Slivers share their abilities, so you play creatures and attack, and the deck does a lot of work on its own. The one thing to learn is tracking which abilities your team has right now, and encore timing after a board wipe.
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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