Squealing Devil

Cast this devil correctly and it punishes you for being mono-red. The third line is a guillotine: spend no black mana to pay its cost and the sacrifice trigger resolves immediately, so the 2/1 leaves play almost as soon as it arrives, leaving behind only whatever the enters-the-battlefield triggers produced. And the pump is not free either; the devil offers the option to pay when it lands, and only if you do does a target creature get +X/+0. So on red alone it functions as a kicker on a stick: pour mana into the boost, take that value, and accept a body that immolates itself. Pay a black mana to satisfy the cost instead (the same two total mana, just colored differently) and the conditional sacrifice resolves harmlessly. The 2/1 survives, carrying Fear, the older and narrower forerunner of menace that slips past anything not black or an artifact creature. This is two-color block design at its most pointed: a card that reads in one color but quietly rewards a second, encoding the off-color as an upgrade rather than a gate. Run it red-only and you buy a one-shot trick; run it with black and the identical cost buys an evasive body that stays on the table. Nothing in the cost line prints the black symbol that unlocks the better mode, which is the whole pedagogical trick of a guild-era hidden incentive: the reward is there for the player who reads past the casting cost.