Silly Bubbles
Necromancer
I have finished all the current chapters and always finish the Spire and as much tournament as I feel like -which is why you need to do all the chapters It is how you upgrade your troops to win the battles
I haven't seen much difference in my Spire or tourney performance either when I progress through the chapters. I'm now in Chapter 18. If anything they have improved a little but that's probably due to other things. I do have a very small number of AW upgrades as I started a new city and thought that I'll try a different strategy so I don't know whether that's got something to do with that.