Thunderhead Gunner

The looter effect is old and cheap: Merfolk Looter has offered "tap: draw, then discard" on a two-mana body for decades, and every rummaging variant since has been priced accordingly. What sets this apart is where the cost sits. Discard-first, draw-after is rummaging rather than looting, which means the card you throw away is chosen before you know what replaces it, and the once-per-turn sorcery-speed clause caps it at a slow trickle. So the natural read is that five mana buys a filtering engine that filters badly, and that would be a bad trade if the engine were the point. It isn't. The body is: a 4/5 with reach is a genuine roadblock, big enough to trade up in combat and tall enough to bracket a flier's attack step, and it does that work whether or not the ability ever fires. The rummage is a floor, not a plan; it turns dead lands and clogged draws into fresh cards on the turns nothing else needs doing, and it feeds any strategy that would rather have cards in the graveyard than in hand. Reading it as a card-advantage engine sells the stat line short; reading it as a beater that never runs out of things to do reads it correctly.