Tapestry of the Ages

Colorless card advantage that gates itself behind behavior rather than a numeric tax: the engine only turns on once you have cast a noncreature spell that turn. That single clause does two jobs. It locks the card out of the most generic homes (a creature-heavy board wanting raw draw gets nothing), and it rewards decks that already chain cheap spells by habit: burn, cantrips, control fillers, the spell-matters builds. The payment structure is honest, too. You spend a card and four mana to deploy it, then two mana and a tap per draw, which makes it a slow grinder rather than an explosive one. And because casting the artifact is itself casting a noncreature spell, the gate opens the moment it enters: with an extra two mana to spare, it can draw the turn it hits the battlefield. The unlock is also more flexible than it looks, because there is no sorcery-speed restriction on the draw. Cast an instant on an opponent's turn, then hold up the two mana to draw at their end step or in response to something, and the engine bends around your tempo instead of pinning you to your own main phase. It sits in a quiet lineage of repeatable card-draw artifacts that ask you to clear a small hurdle each turn rather than pay a flat tax. Making that hurdle behavioral rather than numeric is the cleaner gate: it costs nothing extra to decks already doing the thing, and shuts out the ones that are not.