At the beginning of your upkeep, you may exile Cosima. If you do, it gains "Whenever a land you control enters, if Cosima is exiled, you may put a voyage counter on it. If you don't, return Cosima to the battlefield with X +1/+1 counters on it and draw X cards, where X is the number of voyage counters on it."
Whenever a Vehicle you control deals combat damage to a player, that player exiles that many cards from the top of their library. You may play lands from among those cards for as long as they remain exiled.
Crew 1
Cosima is a mono-blue value engine: exile her on upkeep, ramp lands to stack voyage counters, then return her for a big card-draw burst whenever you choose. Meanwhile The Omenkeel side crews easily and steals lands/spells off opponents' libraries while you build toward a controlling, value-rich board. You win by out-resourcing the table and deploying a big threat or combo finisher.
Repeatable, scalable card draw that refunds itself in mono-blue
Cheap 3-mana commander that doubles as a Vehicle for evasive value via The Omenkeel
Rewards lands-matter and landfall synergies that the deck already wants
Color identity gives access to the best counterspells, card draw, and combo pieces in the format
Card advantage doesn't directly close games—needs a separate win plan
Voyage counter loop is slow and telegraphed; opponents can race you
Mono-blue lacks removal for resolved permanents and has no recursion
Exiling Cosima leaves you without a body and vulnerable on empty boards
Mono-blue's premier ramp/treasure engine to fuel the big plays.
Lean harder into fast mana (Mana Crypt, Sol Ring, Mana Vault) and ritual ramp so the voyage loop and big spells come online a turn or two earlier. Add a compact win condition such as Thrasios + Sword/untapper or a Laboratory Maniac line so the card draw converts to victory, and tighten the interaction suite with Force of Will, Fierce Guardianship, and Cyclonic Rift. Prioritize landfall payoffs and untap effects that abuse the constant land drops.
Legendary Creature — God // Legendary Artifact — Vehicle
