Just Common Towers and Upgrades
New Strategy that I have found with trying more than one tower of soulkeep as it is a game of trying and with every attempt you make then you could do much progress and you could know more about fiends and how you eliminate them in the battle and in any level you play.
I have been able to pass some waves in level 5 and this without losing any heart and this is amazing as when you are to play with towers then you have to know its attacking abilities and how they attack fiends and how much fiends that one tower could eliminate in the way.
I have used some towers that like Gloom Owl and Card Sharp and Fountain of Terror and these ones the common towers that I have used to pass 5 waves without losing any hearts and there in wave 5 and after it in wave 6, I have met Crystal Hand that was a new fiend that with these towers then you can destroy all fiends.
Three Towers that make the difference in this level and when you are to play with them you would be able to pass 4 waves without losing any heart and then you have to think how to pass final waves which by the way so difficult than those first waves and have a huge amount of finds.
So I have discovered that you have to upgrade these towers to be able to get rid of fiends waves and to be in the next level and this is with common towers but if you want to get some epic and rare towers from the market then it would be much easier but with common towers strategy and especially in the last waves then it would be better to upgrade them.