Marketback Walker

The doubled X in the cost is the whole equation: pay X twice and the body arrives as a 0/0 with X counters, so the effective size scales at half the mana you sink in. That inefficiency is the point. This is a variable-cost creature designed to convert leftover mana into a card-draw payload rather than a beater, because the death trigger refunds counters as cards. The activation exists to keep feeding it after it lands, but the real work happens on the way out: whatever counters are sitting on it when it dies become a draw step, so the creature is worth more dead than alive. It rewards being sacrificed, pinged, chumped, or blocked into oblivion, and it punishes an opponent for killing it, since destruction simply cashes the counters into cards. Constructs that ask to die are a small lineage, and most of them lean on tokens or graveyard value; this one leans on a counter count it builds itself, turning the +1/+1 counter (usually a combat stat) into a stored resource that pays out in cardboard. The friction is that it does nothing the turn it enters unless it can profitably trade, and its floor is a fragile blank with no evasion and no immediate impact. Read it not as a threat but as a delayed draw clause bolted to a body that has to die to fire.