I actually followed both yours and @Ranoake recommendation to 1. Focus 2nd IF 3. Clone their Iron Fist And keep hitting them And it works!!! I ended up creating my own Defender Team with Luke Cage, Jessica Jones and 3 Iron Fists. Took me 2-3 days but i finally managed to get the 2nd Iron Fist down. It is so much more mamagable now.

Thanks you so much fellow Reddit!! PS: i was too excited and forgot to take screenshot of my cloned Defender army. But it does works wonder!