East-Mark Cavalier

Deathtouch narrowed to exactly two creature types, and blank against every other board. The destruction is a triggered ability rather than deathtouch keyworded onto the body: whenever this vigilant 2/2 connects with a Goblin or Orc, the trigger goes on the stack and resolves during that same combat damage step, so that creature dies then and there regardless of toughness. Any single point of combat damage becomes a kill, but only against the two tribes the card was built to hunt; across from anything else the ability never checks in, and you are left with an ordinary attacker. The flavor logic (mounted Rohirrim scything through orc-lines) drives the shape, but the underlying design is a conditional, single-color deathtouch pointed at exactly two subtypes. The timing has a hard limit the flavor obscures: without first strike, combat damage is simultaneous, so a Goblin or Orc with 2 or more power kills the Cavalier on the same swing. The destroy trigger still fires and both creatures die, but the trade is even rather than one-sided. Vigilance is the payoff when the Cavalier outsizes what it hits: attacking into a smaller Goblin or Orc kills it outright while the attacker stays untapped, ready to threaten the swing again next turn without ever having to choose between offense and holding the line.