Krovikan Horror
A graveyard card that reads its position rather than just its contents, and that ordering condition is the whole design. The recursion only fires when a creature card sits directly above it in the yard, which turns the pile into a stack where sequence carries mechanical weight: you are not asking "is there a creature in my graveyard," you are asking "did a creature die or get milled after this one." That makes the Horror a self-replaying engine in any deck that feeds the graveyard at the right rhythm, since each creature that lands on top resets the trigger. The neat trick the rules text hides is that the ping can eat the Horror itself: sacrifice it to deal a point of damage, then bury it under another creature card before the end step so it returns to hand, recast, and repeats. But the more durable mode is simpler. Leave the Horror on the battlefield as a repeatable sacrifice outlet, feeding it tokens or other recurring bodies a point of damage at a time, and the self-recursion becomes a fallback rather than the plan. It is among the earliest cards to treat the graveyard as an ordered zone with consequence rather than an unsorted bin, an idea Magic mostly abandoned and only occasionally revisits. The friction is deliberate everywhere: the 2/2 body adds nothing to combat, recursion is gated to the end step and a fussy adjacency clause, and the ping costs both mana and a creature. A puzzle-box of a permanent from an era when designers were still testing how strange a single card's rules text could get.

