I wanted to double check this because Tempered Steel seemed really (too?) strong.
The card reads “Surge - Exhaust this card to add hit”
The surge is not unique so we played it that if I had Tempered available on my Heavy Crossbows I could add more than one hit (if I rolled multiple surges) then exhaust.
So blue surge-surge effectively becomes hit-hit. Dial in the surge modifier and you’ve got the potential for 15 damage at threat three (blue surge-surge, red hit-hit and mod) with Tempered Steel accounting for 9 of that.
However even though the surge is not unique it is an exhaust so does it get exhausted after you spend the first surge? (Thus leaving it unavailable to turn the other two surges into damage)
I suspect the answer is NO and Tempered is just a really good card