Wretched Banquet

The condition does all the pricing here. For a single black mana you get unconditional destruction (no regeneration clause, no "nonblack," no toughness ceiling) on whatever creature sits at the bottom of the power curve. The catch is that you do not pick which creature qualifies; the board does. Against a wide aggressive board of one-power tokens this kills almost anything you point it at, since the floor is low and crowded. Against a single fat threat on an otherwise empty battlefield, that threat is the least power by default, and the spell becomes premium removal. The dead zone is the middle: a developed board where your opponent's good creature outranks a smaller one, and Banquet can only legally hit the small one. That makes it a spell whose quality is set by the texture of the table rather than the card you most want gone, which is an unusual axis for removal to live on. It rewards casting it early (before the board fills out and protects the threat by sandbagging something smaller) or holding it for a topdeck war where the lone surviving creature is necessarily eligible. The line "or is tied for least power" quietly widens the window: a board of identical small bodies all qualify at once, so it is rarely as narrow as the wording first suggests, but it is never the answer you can fire blind.