Hagra Constrictor

The counter-matters archetype usually needs two moving parts working together: a source of +1/+1 counters and a payoff for stacking them. This folds both into one body. It arrives already carrying its own counters, so it switches itself on the moment it lands, and it hands menace to every creature you control that has a counter rather than keeping the keyword to itself. That reach is the design hinge. Menace on a lone attacker is a mild evasion tax; menace spread across a board of counter-stacked bodies is a real blocking math problem, because defenders get eaten two-for-one every time they try to trade. The interaction it wants is proliferate: every creature already holding a counter gets bigger at once, so a board that spent the early turns dropping small counters can, in a single trigger, tip into an attack where every blocker trades down. The tension in the design is that everything runs through the counter, which is also its vulnerability: a creature holding its whole stat line in counters folds to anything that strips them, and removing counters from your team pulls menace off whoever loses their last one. It sits in the functional lineage of aggressive lords that broadcast a keyword to a stacked board, trading raw stats for a combat multiplier that scales with how invested you already are in the counters theme.