Dark Ritual

The original tempo cheat, and the card every mana-positive ritual since has been balanced against. One black to produce three black, a net of two mana, all of it available the same turn, with no strings attached: no discard, no life payment, no creature required, no threshold to meet. That is the frame, stated as plainly as the effect ever gets. Every subsequent attempt has had to bolt restrictions onto it to survive development. Cabal Ritual wants threshold to match the rate. Songs of the Damned counts creatures in the graveyard. Culling the Weak demands a creature sacrifice. Dark Petition triples the cost and ties the ritual to a tutor. The design lesson the card taught Wizards is that an unconditional two-mana profit on the first turn is the line you do not cross again: it accelerates combo kills by a full turn, it pays for hand disruption and a threat in the same window, and it does not scale across a game because the floor and the ceiling are the same card. Banned or restricted in every constructed format where speed matters, and printed at common in the sets where it is legal because the mana math was settled in 1993 and nothing has changed it since.