Horror of Horrors

Regeneration as an enchantment, not a creature ability or an instant. That is the design conceit, and it explains the otherwise eye-watering five-mana price tag: you are not paying for a single save, you are paying once to install a permanent regeneration engine that any black creature on your side can tap into, as long as you keep feeding it Swamps. The shield stays on the table, immune to the creature removal that would normally answer a self-regenerating body like Drudge Skeletons, and the activation cost is a resource (a land) rather than mana, which lets you regenerate at end of turn without compromising your next turn's curve. The catch is the one Legends loved to lean on: it only protects black creatures, and the Swamp tax compounds quickly against any opponent willing to point two removal spells at the same target. The card sits in the same family as the era's other "ability factories," permanents that tried to sell a repeatable creature keyword at enchantment speed before Wizards settled on Auras and Equipment as the cleaner delivery mechanism. The rate did not survive contact with later design philosophy, but the idea (regeneration as a battlefield-wide subscription rather than a per-creature feature) is a genuinely interesting road not taken.