Master of Dark Rites

The tribal tax is the whole design. Skirk Prospector and its kin turn one sacrificed creature into a burst of untyped mana; this one funnels the same act into a color and a spell-type gate, three black that only pays for Vampires, Clerics, and Demons. That restriction is what earns the ratio: a one-mana body converting fodder into triple mana would be reckless without a fence around where the mana goes, so the design ties the payoff to a specific tribal shell rather than leaving it as generic ramp. The result is a sacrifice outlet and a ritual welded together, and it wants a board it can eat: token generators, expendable one-drops, anything that would rather die into mana than sit blocking. The tap in the cost keeps it honest across turns (one activation per untapped cycle unless you have a way to reset it), and the sacrifice clause makes it a genuine outlet for death-trigger and aristocrat lines even when you never spend the mana it produces. What it accelerates toward is the top of a Vampire or Demon curve: cast something that costs far more than the turn suggests, off a creature you were happy to lose. Narrow by construction, and that narrowness is the point; this is a payoff piece for a built-around list, not a mana rock you splash for value.