Whenever Mastermind Plum attacks, exile up to one target card from a graveyard. If an artifact card was exiled this way, create a Treasure token. (It's an artifact with ", Sacrifice this token: Add one mana of any color.")
Whenever you cast a spell, if mana from a Treasure was spent to cast it, you draw a card and you lose 1 life.
Mastermind Plum turns Treasures into card advantage: spend Treasure mana on any spell to draw a card (losing 1 life), so you flood the board with Treasures and chain spells into a grindy advantage engine. Early turns you ramp and set up Treasure production, then attack to exile artifacts from graveyards and bank extra Treasures while drawing through your deck. You win by out-resourcing the table and converting that card advantage into a big mana payoff or a sacrifice/drain finish.
Repeatable card draw in mono-black, a color that historically pays life for cards anyway
Treasure synergy doubles as ramp, fixing, and fuel for the draw trigger
Cheap 3-mana commander that's easy to recast and pressures graveyards on attack
Slots into Treasure-matters and aristocrats shells with strong sac-fodder overlap
Mono-black means no proactive interaction against combo or protection for the engine
Life loss adds up fast and can be exploited by aggro or a mirror life-payment race
The draw trigger requires actually spending Treasure mana each spell, which needs setup
Relies on Treasure makers; without them the commander is just a 2/2 graveyard nuisance
Board wipes hit your Treasure-token base and stall the whole plan
Legendary Creature — Human Wizard
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