Overview:

This UB -1/-1 counters deck leverages Sephiroth's board control and growth potential alongside proliferate engines to execute a grindy attrition strategy. While containing powerful stax elements and combo finishes, it lacks true cEDH-speed wincons and has some critical fragility in its engine pieces.

Primer:

Core Strategy: The deck aims to establish -1/-1 counter dominance through Midnight Banshee/Crumbling Ashes engines, using proliferate from Inexorable Tide and Yawgmoth, Thran Physician to accelerate creature decay. Wincons emerge through:

1. Token Overwhelm: Nest of Scarabs converts counter placement into an insect army
2. Life Drain: Vein Ripper + mass creature deaths
3. Poison: Vraska, Betrayal's Sting ult with proliferate backup
4. Lockout: Toxrill, the Corrosive + Propaganda attrition

Mulligan Priorities:

• Keep hands with 2-3 mana rocks (Mox Diamond, Grim Monolith)
• Require at least 1 counter source (Grim Affliction, Skeleton Ship)
• Prioritize early card draw (Rhystic Study, Baleful Strix) Reject hands without turn 1-2 plays in favor of explosive starts.

Key Tips

• Sequence Yawgmoth, Thran Physician after establishing token producers
• Use Fate Transfer to convert enemy -1/-1 counters into Sephiroth buffs
• Hold free counterspells for critical engine pieces like Crumbling Ashes
• Leverage Opposition Agent to steal tutors for missing combo pieces

Avoid Traps

• Don't overextend Sephiroth, Planet's Heir without protection
• Resist casting Contagion Engine without counter density
• Avoid premature Black Sun's Zenith before establishing recursion

Weaknesses:

Critical:

• No graveyard protection beyond Whip of Erebos (folds to Rest in Peace)
• Engine pieces like Nest of Scarabs have zero redundancy

Moderate:

• Slow recovery from board wipes (only Damnation recursion is Vat Emergence)
• Limited poison acceleration (only Vraska as wincon)

Minor:

• Some dead cards without counter targets (Fate Transfer, Crumbling Ashes)

Most Important Cards:

• Yawgmoth, Thran Physician
• Toxrill, the Corrosive
• The One Ring
• Rhystic Study
• Imperial Seal
• Mox Diamond
• Grim Monolith
• Force of Will
• Fierce Guardianship
• Contagion Engine

Attribute Ratings:

Speed: 6/10

• Fast mana enables T3-4 Sephiroth + counter engines
• No T4 wins, but T6-7 lethal via proliferate/drain

Resilience: 5/10

• Free protection spells but engine pieces lack hexproof
• Slow rebuild after wipe (only 3 recursion effects)

Consistency: 7/10

• 6 tutors + 8 draw engines
• Multiple proliferate triggers ensure counter spread

Interaction: 8/10

• 14 interaction pieces including free counters
• Cyclonic Rift/Toxic Deluge for board control

Rating Justification:

The deck sits between Optimized (T6-7 wins) and Focused Competitive (T5-6) due to:

• cEDH mana base/free interaction but no consult/oracle
• Strong stax elements but no unbreakable locks
• Multiple wincons but none faster than T6 Outperforms casual decks through density of powerful effects but lacks true cEDH speed/protection.

Power level: 6.0 - 6.5