I am too addicted with this game and i can't even put down my phone because of it. I am planning to gain the higher levels without spending some dollars since i want to be fair with others.
And so because of dedicating much of my time and also due to luck i have gain level 26 now in which i also upgraded my marvel characters both heroes and villains to the same level also.
I did a screenshot on my hero list and i am very proud of it.
With my current line up surely i can beat the stages my way up.
If you want to try this game, it is available via Android and iOS.