Marvel United
In S.H.I.E.L.D. solo mode, which card is discarded when a Hero takes damage?
Several solo players agree, and the thread cites the FAQ 2.0 example for three damage.
Any card from the shared solo hand, whichever Hero takes the damage. A BAM! that deals 1 damage to each of three Heroes costs three cards. With no cards left to discard, you are knocked out and lose.