Instill Infection
The friction here is the price tag. A -1/-1 counter is the wither-and-infect ecosystem's native removal currency: it shrinks toughness permanently rather than dealing damage, which means it sticks on regenerators, dodges damage-prevention, and stacks with any other counter the deck is already throwing around. Pairing that effect with a cantrip is the standard cushion designers reach for to make a midrange removal spell feel acceptable even when the rate is soft, and four mana for a single counter is undeniably soft. But the counter is the point in a way the body count never is: against a one-toughness creature it reads as a kill spell that replaces itself, and against anything wearing a +1/+1 counter or two it quietly erodes the math in a way burn cannot. The card is at its most honest when read as a sweetener rather than a workhorse, a removal effect that exists primarily so the deck running -1/-1 counters never has to spend a card to draw one. The cantrip is what earns it a slot at all: it turns a marginal answer into card-neutral interaction, smoothing a grindy game without ever swinging it.
