Broodlord

One value of X, spent twice. Ravenous parks X +1/+1 counters on the Broodlord's own 3/3 (with a card off the top once X hits five), and Brood Telepathy then hands out the same X in counters across your other creatures. You are not splitting a pool or choosing between the two; both fire in full off the same number, so a large X is a double investment rather than a divided one. That is what makes it scale the way it does. Early, it is a modest body that reinforces a small board. Late, it arrives as a fat threat that also seeds a second wave, doubling its counter output at the exact point in the game when a wide field is waiting to receive it. The distribution half rewards a counter-matters shell more than a single overloaded creature, since those counters keep their value after the Broodlord dies while the body's own stack of counters walks to the graveyard with it. Directing the payoff to permanents that outlive the caster is the real strategic axis here: the card is at once a finisher and a way to bank X into the rest of your board, and a green counters deck gets to treat every point of X as spent in two places at once.