I made a budget deck to beat Shinkage Zendo, one of the most difficult bosses. Unfortunately I am on a trip so I could not record the game, therefore only a text guide.
I used Kaleos for this boss because of his BBS and Flamewreath. It looked almost like this version I linked here except that I did 2 minor changes because I was not happy with the cards (replaced Mystic with Herald and Giago with Daywatcher).
How to play:
It is very important to keep your general away from Shinkage. For that use Silhouette Tracer and always park one of your own minions 2 tiles in front of your general. As soon as Shinkage starts using their BBS you are usually safe because they summon wraithlings at the right top corner and your general runs there.
You need a Wild Tahr or a Flamewreath next to that corner to kill all Wraithlings every turn they appear. If you don’t do that it usually happens that the wraithlings run in the other corner and you have more work hunting them down. After Kaleos always hits the nearest wraithling I moved Wild Tahr or Flamewreath on the now empty spot and killed the other 3. After that I used my BBS to keep them away from the creep tile and have them survive longer.
Usually Wild Tahr is excellent against bosses, because they always attack something. But because you don’t put any minions next to Shinkage to prevent free trades for them and their minions often being very defensive, Wild Tahr’s attack doesn’t get buffed often. But they are still great to clear wraithlings.
This deck has a lot of ping and removal to help clearing board every turn. Ranged minions are great because they can attack Shinkage after clearing board or help clearing board without hurting your own board.
Often you build up a board till you can kill Shinkage in one turn. Ranged minions help whittling him down. Though be aware Shinkage plays Phoenix Fire.
Be aware that Shinkage plays Quartermaster Gaujj, you need a Thunderbomb or 2 Gotatsus /Ghost Lightnings for that to answer. Otherwise this minion can screw you over
If you have any questions, just ask me!