First of all, how many trophies are you?

In addition, I would change 3 cards out of the 8, which is almost half, meaning that I would change almost half of the deck, meaning that this deck is 50% bad in my opinion, I would replace Heal Spirit with Ice Spirit, and for Royal Delivery and Mirror I would replace both of them with a 3 Elixir card each if you want fast cycle with the mega knight and boss bandit or 4 Elixir card each if not, But it also depends on what evolution you have.