Boneknitter

This black tribe was built around the promise that Zombies do not stay dead, and here is the engine room of that promise: a repeatable regeneration shield for any Zombie, including itself. Regeneration as a Zombie payoff is tidy flavor-mechanics alignment (the things that already shrug off death get armor against it), but the real design value is durability for a tribe that grinds toward a win through attrition. Each shield costs and saves only one Zombie per activation, so the rate stays honest; against a sweeper that does not stop regeneration, that two-mana toll per body becomes a bottleneck rather than a blanket save. The morph cost is the quieter decision. A 1/1 body that wants to hang back feeding mana into its ability is fragile and announces its job the moment it lands, so a face-down cast lets it sit anonymously among your other unflipped permanents, off the radar of targeted removal, until a regeneration actually matters; the flip cost is cheap enough to leave mana for an activation the same turn. The whole package is less a beater than a maintenance unit: a Cleric whose work is keeping the horde standing through combat and sorcery-speed removal, one regeneration at a time.