Spined Tyrranax

A 5/5 for five is the floor, but the design puts the money in the optional combat trigger: pay and one creature gets a lasting counter plus trample for the turn. Two things about that construction are worth pulling apart. First, the counter lands on any creature, not just this Dinosaur, so the payment works as a mana sink that scales your whole board rather than pumping a lone attacker; the trample rider then pushes the swelling creature through a chump instead of stalling it out. Second, the timing is doing quiet work. The trigger comes at the top of combat, before attackers are declared, so you commit the mana with your untapped state known but the defender's blocks still hidden. That is a deliberate front-load: you buy the counter and trample as an opening move, not as a reactive answer to a bad block. A repeatable, mana-hungry counter engine is a familiar green shape, a body that converts surplus mana into permanent stats every turn. What keeps it from stalling behind a single wall is the trample grant: it means the sink stays live in a clogged board where a plain pump would just pile power against a defender. It punishes a plan that hopes to hold mana up for something reactive, and it plays best when you already want to be attacking.