God-Eternal Kefnet + Isochron Scepter + Brainstorm + Walk the Aeons

4-card combo · U

Verdict

Yes — this 4-card loop gives mono-blue infinite turns as long as 4 mana and a scepter activation are available each cycle.

Cards required: 4
Cheapest stack total: $23.74
Color identity: U
Popularity: 126 decks
Format: Commander

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God-Eternal Kefnet's replacement trigger copies Walk the Aeons off the top of the library for 2UU; Isochron Scepter imprinting Brainstorm is the reset button that puts Walk the Aeons back on top every turn. The loop is mono-blue, runs through the draw step, and locks the table out as soon as the engine is assembled — the extra-turns shell with Kefnet as commander is the natural home.

Recipe

How it works

Prerequisites

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Steps

During the end step before your turn, activate Isochron Scepter by paying and tapping it, casting a copy of Brainstorm without paying its mana cost.
Resolve Brainstorm, causing you to draw three cards and put Walk the Aeons and another card on top of your library, ensuring Walk the Aeons is the topmost card.
Move to your turn, drawing and revealing Walk the Aeons during your draw step.
God-Eternal Kefnet's first ability triggers, causing you to pay to cast a copy of Walk the Aeons.
Resolve the copy of Walk the Aeons, causing you to take an extra turn after this one.
Activate Isochron Scepter by paying and tapping it, casting a copy of Brainstorm without paying its mana cost.
Repeat from step 2.

Result

Infinite turns; Lock

Variations

Cheaper, tighter, alternate lines

Temporal Manipulation or Time Warp can substitute for Walk the Aeons as the imprinted Scepter target if the goal is a simpler Kefnet trigger without the Brainstorm reset — though that line needs the extra-turn spell in hand rather than in the library. Mystical Tutor and Muddle the Mixture both fetch Brainstorm or Isochron Scepter to assemble the engine faster; Whir of Invention finds the Scepter at instant speed.