Diregraf Escort
A green one-drop built almost entirely as a hate card, stapled to a mechanic that makes the hate conditional. Soulbond turns the protection from Zombies into a two-for-one umbrella: pair this 1/1 with anything, and both bodies become untouchable by the tribe it was designed to wall out. That conditionality is the whole balancing act. You can deploy it early and pair later, or hold it to bond with a more important threat the moment that creature lands, but the protection vanishes if either half of the pair dies or leaves. So the card asks you to keep both pieces on the board to keep the benefit, a steeper commitment than a sideboard answer that simply sits in play doing its job. And the protection is the only thing soulbond shares here: the keyword does not hand each partner the other's abilities, only the specific protection printed on this card, so the bonded creature gains nothing but the shield against Zombies. That makes the body a real liability when the pairing is dead weight, because a 1/1 with no protection target is just a 1/1. Protection from Zombies is narrow by construction, built for a metagame where one creature type is doing enough damage to warrant a dedicated answer that still leaves a body on the table when the matchup it hates never shows. It is a clean illustration of pairing a single-purpose protection effect with a mechanic that demands you keep the pair together, rather than handing the keyword out for free.
