Wellgabber Apothecary

The activation cost names its constituency outright: prevent all damage to a single creature, but only if that creature is tapped and only if it belongs to one of two adjacent tribes. The tapped clause is the whole pivot. White and blue tribal aggro of this era wanted to attack, and the price of attacking is that your creature commits to combat and trades with whatever blocks it. This Cleric sells insurance against precisely that exchange: swing with your Merfolk or Kithkin, then keep an attacker alive through a block it would otherwise lose. Because it works at instant speed and repeats, it lets you overturn combat math the opponent thought they had settled, walking a creature through a double-block or trampling intent intact. The friction is that each activation shields one attacker and leaves everything else exposed, which keeps a five-mana 2/3 from warping anything: you pay real mana, one creature at a time, to undo the trade that aggression normally costs. As tribal-support design it is narrow by intent, a glue card for two tribes rather than a standalone threat, and its ceiling is entirely a function of how many attackers it is asked to shepherd through hostile blocks.