Vedalken Anatomist

The activation cost is the whole calculus here: plus the tap of the body itself, every turn, to drop a single -1/-1 counter. Where most repeatable shrink effects fire for free or for one mana, this one demands a full hand of resources to chip away one toughness at a time, which is why it leans on accumulation against bigger creatures rather than swift removal. The genuinely unusual rider is the tap-or-untap clause stapled to each counter, and crucially it operates on the same creature receiving the counter. Point it at an opposing creature and the two halves stack cleanly: you erode its toughness and, by tapping it before combat, keep it from attacking or deny it as a blocker. Over several turns the counter math and the forced tap state compound on the same target until it is small and idle at once. The untap mode is the awkward sibling, since untapping the creature you are shrinking mostly helps it (letting an opponent's creature stand back up to block), so it rarely earns the activation; it exists for the corner case of freeing one of your own creatures while paying the toughness tax. It belongs to a lineage of persistent shrinkers given a Phyrexian cast here, where cheap bodies grind toughness away one point at a time; the tap manipulation is the second axis those plain counter-stackers lack. A 1/2 that must commit its tap, at a steep price per use, will never race anyone. It is built for the grind.