Overview:

This mono-black deck leverages Karumonix, the Rat King to helm a synergistic Rat tribal strategy focused on overwhelming opponents through combat damage amplified by Rat Colony's scaling power and poison counters via Toxic 1. The commander enables card advantage by tutoring Rats on ETB while granting the entire tribe poison. The deck supports this with aristocrats payoffs (e.g., Zulaport Cutthroat, Blood Artist), exponential token generation (Marrow-Gnawer, Lord Skitter, Sewer King), and potent finishers like Thrumming Stone for explosive Rat Colony chains. Karumonix is essential as both a card advantage engine and poison enabler—removal significantly slows the deck's momentum despite low commander cost.

Primer:

Core Strategy Execution:

1. Early Setup (Turns 1-3): Deploy mana accelerants (Jet Medallion, Dark Ritual, Crypt Ghast) or low-cost Rats (Rat Colony, Lord Skitter's Butcher). Prioritize establishing Urborg, Tomb of Yawgmoth + Cabal Coffers/Cabal Stronghold for mana scaling.
2. Commander & Board Development (Turns 3-5): Cast Karumonix, the Rat King to refill with Rats. Generate tokens via Lord Skitter, Sewer King or Ogre Slumlord. Equip Skullclamp/Whispersilk Cloak for draw/unblockability. Use Plumb the Forbidden for instant-speed draw/sacrifice synergy.
3. Win Condition Execution (Turns 4-7):
   • Combat/Poison: Swarm with buffed Rats (Ashcoat of the Shadow Swarm, Patchwork Banner). Leverage Toxic 1 for incremental poison.
   • Aristocrats: Sacrifice Rats to Ashnod's Altar/Altar of Dementia while draining with Zulaport Cutthroat/Bastion of Remembrance.
   • Explosive Finishers: Resolve Thrumming Stone to chain Rat Colonies for lethal combat or mill via Altar. Activate Bolas's Citadel or Marrow-Gnawer for game-ending plays.

Mulligan Priorities:

• Keep hands with 2-3 lands (prioritize Urborg, Cabal Coffers, or color-fixing like Expedition Map).
• Require early plays: 1-2 Rats, ramp (Jet Medallion, Dark Ritual), or card advantage (Skullclamp).
• Avoid hands lacking Rat density or mana acceleration.

Key Tips:

• Maximize Karumonix: Cast him after board wipes to rebuild instantly. Protect him with Swarmyard or Whispersilk Cloak to ensure repeat triggers.
• Sacrifice Timing: Use Ashnod's Altar/Altar of Dementia in response to removal or with aristocrats on board. Plumb the Forbidden can draw 5+ cards post-wipe.
• Combo Potential: Thrumming Stone + Rat Colony often wins on the spot. Marrow-Gnawer + 3+ Rats generates exponential tokens for sacrifice or combat.
• Recovery: Patriarch's Bidding and Ashcoat of the Shadow Swarm rebuild from graveyard hate or wipes.

Weaknesses:

Critical

• Board Wipes: Mass removal (e.g., Damnation) decimates Rat tokens/Colonies, requiring significant resources to rebuild.
• Graveyard Hate: Rest in Peace/Leyline of the Void cripple Patriarch's Bidding, Ashcoat, and recursion.
• Anti-Tribal: Engineered Plague/Plague Engineer naming Rats annihilates the board.

Moderate

• Artifact/Enchantment Removal: Losing Thrumming Stone, Skullclamp, or aristocrat payoffs slows the deck drastically.
• Mana Base Disruption: Blood Moon/Field of Ruin targeting Urborg/Coffers severely limits mana generation.

Minor

• Spot Removal: Killing key lords (Ashcoat, Marrow-Gnawer) is manageable due to redundancy but delays wins.
• Life Loss: Bolas's Citadel and painlands can pressure life totals against aggressive pods.

Most Important Cards:

• Thrumming Stone (Instant-win enabler with Rat Colony)
• Karumonix, the Rat King (Card advantage, poison enabler)
• Marrow-Gnawer (Exponential token generation)
• Ashcoat of the Shadow Swarm (Board buff, recursion)
• Cabal Coffers + Urborg, Tomb of Yawgmoth (Mana scaling)
• Skullclamp (Draw engine for 1-toughness Rats)
• Patriarch's Bidding (Mass reanimation)
• Zulaport Cutthroat/Blood Artist (Aristocrats drain)
• Ashnod's Altar (Sacrifice outlet, mana)
• Plumb the Forbidden (Instant-speed draw/sacrifice)

Attribute Ratings:

Speed: 7/10

• Capable of T4-5 wins via Thrumming Stone chains or Marrow-Gnawer tokens, though poison wins typically take longer (T6-7).

Resilience: 5/10

• Recursion (Bidding, Ashcoat) and protection (Swarmyard) offer recovery, but board wipes/grave hate cause severe setbacks.

Consistency: 7/10

• High Rat density and Karumonix's tutor ensure early threats; lacks non-creature tutors beyond Demonic Tutor.

Interaction: 4/10

• Limited removal (Oubliette, Kindred Dominance); relies on stax-like effects (Dictate of Erebos) over counterspells.

Rating Justification:

The deck achieves T4-5 wins with high-roll hands (Thrumming Stone) and consistently pressures life/poison by T6-7, aligning with Focused Competitive benchmarks. However, its vulnerability to common disruption (wipes, grave hate) and lower interaction density prevent higher optimization.

Power level: 6.5 - 7.0