Overview:

This Dimir deck is helmed by Umbris, Fear Manifest and Falthis, Shadowcat Familiar, focusing on exiling opponents' cards to amplify Umbris into a lethal commander damage threat while disrupting enemy strategies. The primary game plan leverages Horror/Nightmare tribal synergies (enhanced by changelings like Changeling Outcast and Maskwood Nexus) to trigger mass exile effects from Umbris and support cards like Ashiok, Dream Render. Secondary win conditions include mill via Fractured Sanity/Psychic Corrosion, life loss with Guiltfeeder, and stax locks using Leyline of the Void/Planar Void. Umbris is the linchpin, benefiting from cost reduction based on your highest-power creature, while Falthis grants it evasion (menace) and deathtouch. The strategy is vulnerable to commander removal but includes equipment-based protection and recursion.

Primer:

Core Strategy Execution:

1. Early Setup (Turns 1-4): Deploy mana rocks (Sol Ring, Arcane Signet) and low-cost Horrors/changelings (e.g., Changeling Outcast, Benthic Infiltrator) to trigger Umbris's exile effect. Cast Umbris early using cost reduction, protecting it with Lightning Greaves or Swiftfoot Boots.
2. Mid-Game Engine (Turns 5-7): Resemble value engines like Sire of Stagnation or Rhystic Study to draw cards while exiling. Use Toxrill, the Corrosive for board control and Opposition Agent to hijack tutors. Amplify Umbris with Falthis' deathtouch/menace.
3. Win Conversion (Turns 7-9):
   • Commander Damage: Equip Umbris with Whispersilk Cloak or activate Rogue's Passage for unblockable lethal strikes.
   • Mill: Chain Fractured Sanity with Maddening Cacophony or Psychic Corrosion to deplete libraries.
   • Stax Lock: Pair Leyline of the Void with Mindcrank to exile graveyards and punish life loss.

Mulligan Priorities:

• Keep hands with 2-3 lands (including UB sources), 1-2 ramp pieces (e.g., Sol Ring, signets), and an early Horror/changeling or protection (e.g., Swiftfoot Boots). Prioritize Leyline of the Void or Dauthi Voidwalker against graveyard decks. Avoid hands lacking ramp or exile triggers.

Key Tips:

• Evasion is Critical: Use Falthis' menace and equipment like Winged Boots to ensure Umbris connects. Maze of Ith protects Umbris during attacks.
• Leverage Exiled Cards: Dauthi Voidwalker and Opposition Agent let you cast opponents' exiled cards for additional value.
• Timing Matters: Hold counterspells (Fierce Guardianship, Swan Song) to protect key pieces like Umbris or stax enchantments from removal.
• Toxrill Control: Deploy Toxrill, the Corrosive against wide boards; use its Slug tokens for card draw or chump blocking.

Weaknesses:

Critical

• Artifact/Enchantment Reliance: Removal of key stax pieces (Leyline of the Void, Psychic Corrosion) or protection equipment cripples the exile engine and Umbris survivability.
• Board Wipe Vulnerability: Lacks mass recursion; rebuilds slowly after wipes (e.g., Cyclonic Rift is the only reset).
• Anti-Exile Hate: Rest in Peace or Dauthi Voidwalker (opponent-controlled) halts Umbris growth and mill payoffs.

Moderate

• Mana Constraints: Limited ramp (only 4 rocks) struggles to cast high-CMC threats like Toxrill or Arvinox early.
• Graveyard Dependency: Recursion (e.g., Nightmare Shepherd) is foiled by incidental graveyard hate.
• Combo Inefficiency: Mill/combat wins require setup; vulnerable to interaction during slow buildup.

Minor

• Single-Target Removal: Spot removal can disrupt utility creatures but is mitigated by counterspells and redundancy.
• Flying Threats: Limited reach; relies on Mist Intruder or Sludge Monster for air defense.

Most Important Cards:

• Umbris, Fear Manifest (Commander damage wincon; exile engine enabler)
• Leyline of the Void (Stax piece; fuels Umbris and disrupts opponents)
• Dauthi Voidwalker (Exiles graveyards; steals opponents' spells)
• Toxrill, the Corrosive (Board control; creates blockers and draws cards)
• Sire of Stagnation (Exiles on land drops; draws cards)
• Opposition Agent (Tutor denial; steals opponents' searches)
• Cyclonic Rift (Board wipe; enables alpha strikes)
• Rhystic Study (Card draw engine; maintains hand advantage)
• Whispersilk Cloak (Ensures Umbris connects with shroud/unblockable)
• Ashiok, Dream Render (Exiles graveyards; mills and shuts down searches)

Attribute Ratings:

Speed: 5/10

• Can threaten wins via commander damage or mill around turns 7-9, but high-CMC cards and incremental exile slow early pressure.

Resilience: 6/10

• Protection equipment and counterspells shield key pieces, but reliance on Umbris and fragile stax enchantments creates recovery gaps after removal.

Consistency: 7/10

• Redundant exile effects (Horrors, Ashioks, mill spells) and card draw (Rhystic Study, Sire of Stagnation) reliably advance the game plan, though tutor density is low.

Interaction: 8/10

• Robust suite: counterspells (Mana Drain, Fierce Guardianship), targeted removal (Reality Shift, Ravenform), and stax (Opposition Agent, Phyrexian Revoker) handle diverse threats efficiently.

Rating Justification:

This deck demonstrates focused synergy and strong interaction, enabling T7-9 wins via commander damage or mill, but its reliance on setup turns and vulnerability to stax removal caps its speed. Resilience from protection and disruption aligns with optimized casual tiers, though mana constraints prevent higher consistency.

Power level: 5.5 - 6.0