An upgraded Speedster can trivialize some otherwise threatening fights in a deck with a few copies of cards like Acrobatics, Calculated Gamble, Adrenaline, and Prepared. If you're not in a fight it's good in, you have a 7-Card starting hand, so you don't need to play it. It's a much much worse card unupgraded, because the cards it works best with often exhaust the first time they're played.
