Halana and Alena, Partners

The combat trigger fires at the beginning of combat, one step ahead of the attack declaration, so the counters and haste land while there is still time to send the newly enlarged creature in that same turn. A fresh body drawn this turn can pick up the whole pile and swing immediately. The size of that pile keys off Halana and Alena's own power, not the target's, and that detail redirects deckbuilding back at the pair themselves. The way to escalate is to make the rangers bigger, so any counter-doubling or power-pump aimed at them enlarges every future handoff at once. The teammate benefits from the counters but does not feed the engine; growth lives in the source, not the recipient. Two-headed legendary designs like this lean on the fiction of paired hunters to justify one card doing a double-creature's job, and the counter engine is the mechanical form of that partnership: one body holds the line while the other's power decides how large the next attacker gets. Reach and first strike on a 2/3 are the defensive half of that split, letting the pair block fliers and trade up while the real work compounds elsewhere. The dependence on a valid target is the honest limit: with an empty board this is a small blocker with nothing to hand off, and that constraint stops a repeatable counter engine from being a four-mana coronation on its own.