Strike back is supposed to force your opponent to always play first.
I've noticed it doesn't always do this based on what type of bonus/abilities the other cards have. if you have one cancel bonus in your 4 cards then I have seen strike back not work at all. its a bug I think.
Leader cards are somewhat useless now because some of the newer cards coming out will most likely have the same powers from the second you get them. Like Bridget's 1 life is now a starting ability for perle (sorta) only difference is perle gives you life per opponents damage level and bridget gives it to you for every round (so its guranteed 4 lives).
In my mind I see Perle as a better card. she is also a level 5.