Overview:

This mono-black deck is built around Marrow-Gnawer, leveraging a Rat tribal strategy focused on swarming the board with tokens and amplifying Rat Colony's power-scaling effect. The commander serves as the core engine, enabling exponential token generation by sacrificing a single Rat to create X tokens (where X is your current Rat count). The deck wins primarily through combat with massive Rat Colonies, supplemented by aristocrats drain effects (e.g., Blood Artist, Valley Rotcaller), poison via Karumonix, the Rat King, and occasional finishers like Eldrazi Monument. Marrow-Gnawer is indispensable to the strategy, enabling explosive turns but making the deck highly vulnerable to commander removal.

Primer:

Core Strategy Execution:

1. Early Setup (Turns 1-3): Deploy mana accelerants (Sol Ring, Jet Medallion, Arcane Signet) and low-cost Rats (Typhoid Rats, Rat Colony, Voracious Vermin). Prioritize establishing Herald's Horn or Vanquisher's Banner for cost reduction/card advantage.
2. Commander & Engine Activation (Turns 4-5): Cast Marrow-Gnawer (ideally with protection like Lightning Greaves). Use its ability to sacrifice a Rat and double your token count. Leverage Swarmyard for regeneration or Patriar's Seal to untap Marrow-Gnawer for multiple activations.
3. Board Amplification (Turns 5-7): Deploy lords like Karumonix, the Rat King, Lord Skitter, Sewer King, or Ogre Slumlord to boost Rat stats/abilities. Use Crippling Fear or Kindred Dominance for selective board control.
4. Win Condition Execution:
   • Combat: Swing with a massive army of Rat Colonies (each gets +1/+0 per other Rat). Eldrazi Monument grants flying/indestructible for an alpha strike.
   • Aristocrats: Sacrifice Rats to Ayara, First of Locthwain, Deadly Dispute, or Village Rites, draining opponents via Blood Artist/Valley Rotcaller.
   • Poison: Connect with toxic Rats from Karumonix.
   • Recursion: Recur key Rats with Echoing Return or Mudflat Village for sustained pressure.

Mulligan Priorities:

• Keep hands with 2-3 Swamps and early ramp (Sol Ring, Jet Medallion).
• Prioritize at least one 1-2 mana Rat (e.g., Rat Colony, Typhoid Rats) and Marrow-Gnawer enablers (Herald's Horn, Lightning Greaves).
• Avoid hands lacking acceleration or with only high-cost cards (e.g., Kindred Dominance).

Key Tips:

• Protect Marrow-Gnawer: Equip Greaves immediately. Use Swarmyard to regenerate it in response to removal.
• Maximize Token Synergies: Sacrifice tokens to Ayara for card draw or to Plunge into Darkness for life gain/tutoring. Black Market scales with deaths for massive mana.
• Leverage Critical Mass: Activate Marrow-Gnawer only when you have 5+ Rats for explosive value. Songs of the Damned converts a full graveyard into game-winning mana.
• Recover from Wipes: Revenge of the Rats and Haunted One (undying trigger) help rebuild after board clears.

Weaknesses:

Critical

• Commander Dependency: Removing Marrow-Gnawer cripples token generation and slows the deck drastically.
• Board Wipes: Mass removal (e.g., Damnation) devastates the Rat swarm with limited recovery outside Haunted One.
• Graveyard Hate: Rest in Peace shuts down recursion (Echoing Return, Songs of the Damned, Revenge of the Rats).

Moderate

• Artifact/Enchantment Removal: Losing key engines (Herald's Horn, Vanquisher's Banner) reduces consistency.
• Flying/Evasion Threats: Struggles to block airborne armies without Eldrazi Monument.
• Stax Effects: Cursed Totem disables Marrow-Gnawer's tap ability and other activated synergies.

Minor

• Mana Base Fragility: Non-Swamp utility lands (Bojuka Bog, Witch's Cottage) may enter tapped, slowing early plays.
• Limited Stack Interaction: Minimal counterspells make resolving key spells risky against blue decks.

Most Important Cards:

• Marrow-Gnawer (Token generation engine)
• Rat Colony (Primary threat, scales with Rat count)
• Karumonix, the Rat King (Tutor, poison enabler)
• Eldrazi Monument (Combat finisher)
• Blood Artist (Aristocrats payoff)
• Cabal Coffers (Mana amplification)
• Herald's Horn (Cost reduction & card advantage)
• Vanquisher's Banner (Anthem & card draw)
• Ogre Slumlord (Token generation & deathtouch)
• Ayara, First of Locthwain (Card draw & life drain)

Attribute Ratings:

Speed: 6/10

• Can threaten wins via combat or drain around turns 7-8 with an unimpeded Marrow-Gnawer activation, but relies heavily on setup.

Resilience: 4/10

• Limited protection for Marrow-Gnawer and few ways to recover from wipes. Recursion exists but is slow and graveyard-dependent.

Consistency: 7/10

• High Rat density and cost-reduction artifacts ensure early plays, but tutors are scarce (only Karumonix/Ratcatcher).

Interaction: 3/10

• Minimal targeted removal (Feed the Swarm, Defile) and no counterspells. Relies on board wipes like Crippling Fear for control.

Rating Justification:

The deck achieves focused combat/aristocrats wins around T7-8 with strong synergy but suffers from critical commander dependency and low interaction. Its speed aligns with Focused tiers, while fragility prevents higher optimization.

Power level: 5.5 - 6.0