Mob

Convoke on a destroy-target-creature spell is the whole idea: the printed cost of five mana is a fiction the card almost never pays. In a board state wide enough to want unconditional removal, the same creatures that make the spell expensive to hard-cast are the ones that tap to bankroll it, so a five-mana instant collapses toward zero as your side of the battlefield grows. That inverts the usual scaling of removal, which gets worse the further behind you fall; this gets cheaper the further ahead you are. The design logic is that black rarely gets clean, unconditional destruction at instant speed without a rider (a life payment, an edict clause, a can't-regenerate caveat that trims the odd creature), and convoke is the substitute tax here, paid in board presence rather than mana or life. The catch is that it wants a board you may not have when you most need the removal: against the aggressive starts that punish a slow answer, you have the fewest bodies to convoke with, and against control you have plenty of creatures but less need to trade them. It is removal built for the go-wide midrange mirror, where two developed boards stare at each other and the player who can spend an attacker or two to erase a blocker breaks the stall. Read that way, the five in the corner is less a cost than a ceiling.