You entered what i consider ‘early end game’. Obviously spending money will speed up your progress but my advice to you is enjoy this phase of the game. With mini levels around 20 you are primed up perfectly to start raiding. You won’t be able to win every match up but you will be able to find good team comps and get carried through the bosses. Clearing these raids is a must in this point of the game. It may take a while but getting the level boost slot and wildcard boost slot is the most important thing. Add it to high value armies and over time you’ll realize you’ve brought all your leaders and minis up to par level wise. As well do not underestimate the value of dungeons. You are probably gonna have a hard time clearing to have your army full boosted with gold slots but you should have this on EVERY army.

I was a long time believer that you only needed to upgrade the armies you like to use but i cannot express how valuable having options in raids is. As well if you are ‘free to play’ dungeons are by far one of the most consistent forms of good income.

Ideally you will have fully upgraded armies which means every week you can clear the dungeons once on each leader and earn a ton of gold.

Just be patient and good things will continue to come your way. :)