This is a fair card, but it compares poorly to Make the Call, admittedly one of the best non-hero cards in the game. There are two theoretical advantages. One is that you can activate abilities of allies that only trigger when played from hand such as Beak and Shadowcat. Another is that this is a support which can sit in play until the perfect moment - something that is always an advantage of upgrades/supports compared to events with similar effects. Neither of these points would lead me to play copies of Won't Stay Down over Make the Call, but if I'm already playing 3 Make the Call, ally recursion is a strong enough effect to play a copy or two - finding Professor X or M at the perfect moment, for example. Sunspot is another interesting ally who is one of few payoffs for a -based deck and only gets his ability when played from hand. Won't Stay Down doesn't have an energy resource, which might be a deal-breaker for the strategy, but this deck would theoretically want to play Sunspot as many times as possible.