Question: how to unlock characters in marvel puzzle quest?
Answer: Open the game by tapping on the 'Puzzle Quest' icon on your device.
Tap on 'Recruit Heroes' which will be at the bottom left corner of the screen.
You will find several options to buy 'Hero Cards. ' They will cost you hero points. ... 
After you tap on any card of your choice. ... 
Tap on that pop-up to buy that particular card.