Scour the Laboratory

Six mana to draw three cards is a rate nobody plays; four mana to draw three at instant speed is the floor for a serious refill spell, and delirium is the bridge between those two numbers. The discount is unconditional once the graveyard holds four card types, which reframes the cost as a deckbuilding checklist rather than a tax: spread your bin across creatures, instants, sorceries, lands, and whatever else feeds it naturally, and the spell pays you back with a full hand the turn you hit the threshold. What makes the design coherent is that the conditions a delirium deck wants anyway (cheap creatures dying, spells cycling into the yard, fetched or sacrificed lands) double as the switch that turns this on. The instant-speed clause matters more than the headline draw: you can hold it open through an opponent's turn, resolve it on their end step once delirium is live, and untap into a refueled hand while your own main phase stays clear for threats. It belongs to a family of delirium payoffs that rewarded graveyard diversity over raw graveyard size, a distinction that shaped how those decks were built: you were never dumping cards indiscriminately, you were curating a spread, because the fourth card type was worth as much as any card in hand.