Dark Banishing

Black's recurring tax for unconditional removal has always been color: the strongest kill spells in the color refuse to point at black creatures, and this is the clean three-mana expression of that rule. Destroying any nonblack creature and shutting off regeneration in the same instant is a generous rate for the era, but the carve-out is the whole design. It encodes black's identity not as the color that kills everything, but as the color that kills everything except its own, leaving mirror matches to be settled by something other than a single removal spell. The regeneration clause does real work too: in a period when shroud was rare and indestructible did not exist, the only common way a creature dodged a "destroy" effect was by regenerating, so "can't be regenerated" was the language that closed the loophole rather than the redundant boilerplate it reads as today. Functionally it is the black analog to a clean point-and-kill instant, with the nonblack restriction standing in for the converted-cost or toughness ceilings other colors used to keep their removal honest. Wizards has reprinted and revisited the template often, refining the rate downward over the years, but the structural idea (uncondition removal walled off by the caster's own color) traces straight back through cards like this one.