Tome of Legends

Card advantage keyed to the one permanent every Commander deck is guaranteed to run. The book starts with a stored draw and refills every time your commander enters or attacks, which means it pays out along two axes at once: the recasting you were already doing to survive commander tax, and the aggression you were already committing to by swinging. Neither is a new demand on the deck; both are behaviors a commander is built to do anyway, so the counters accumulate as a byproduct rather than a cost. The activation is the throttle: one mana and a tap per card, one counter spent at a time, so this is a slow trickle rather than a burst refuel. That pacing is the trade for how cheap and how universal the trigger is. The catch is that it has no floor without a commander on the battlefield; the stored page it enters with is the only card it ever guarantees. It rewards decks whose commander lives in the red zone or bounces in and out of the command zone, and does nothing for the durdle pile that leaves its general parked at home. This is one of a handful of colorless artifacts written specifically for the singleton-general format, engines that would be unprintable in a deck without a commander because their entire economy is denominated in commander triggers.