Werebear

A mana dork that promises to become a beater is a strange contract, and it's the one that made Threshold legible as a mechanic. For the early turns it just makes green mana, a 1/1 body fueling whatever you're casting; the trick is that the casting also fuels the dork. Spent spells, cantrips, fetched lands, and dead creatures all pile into the graveyard, and once seven are there the accelerant stands up as a 4/4. The reward isn't a separate payoff card you have to draw: it's the same body you've been tapping for mana since turn two, now worth swinging with. That double duty made it the signature common of its mechanic, the card that taught players to read their own graveyard as a counter rather than a discard pile. The catch is the toughness floor while you wait. Below threshold it dies to almost anything, and unlike the recurring green fatties of its era (the kind that return from the graveyard already at full size), it has to grind the count up before it can hit hard. A fragile accelerant that opponents are happy to pick off early, and a threat that only earns its body if it survives: that tension is what makes it a card to build around rather than merely play.