Kry Shield

A defensive trade rendered as a single activation, and the trade is stranger than it looks. The prevention clause does not protect your creature from harm: it stops all damage the creature itself would deal, which means activating Kry Shield turns your blocker into a wall that survives the combat but lands no return blow. What keeps that wall alive is the second half, a toughness boost scaled to the creature's own mana value, so the more expensive the creature you point this at, the more incoming damage it can soak. The logic is symmetrical in a way that reveals the era's design instincts: you surrender the creature's offense to maximize its defense, paying the cost again whenever you want to repeat the trick. It is built for one narrow combat puzzle, holding the line against a large attacker without losing the blocker, and the conditional shape (prevention that disables your own damage, toughness that scales with cost rather than with the threat across the table) is exactly why it stayed a curio. Later sets solved the same problem more cleanly: removal, instant-speed pumps, and fog effects that do not handcuff the creature you are trying to save. The willingness to print an artifact this specifically tuned, doing two jobs that interlock only under a precise set of board conditions, is part of what makes the design vocabulary of Magic's earliest expansions read so differently from anything printed since.