Gym Leader Challenge is a popular example and is one of many listed in the Alternative Play Handbook linked below
If you have a Food Chain deck with access to red like my Prossh, Skyraider of Kher deck, Dominaria s version of Squee will do some good work for you
While this looks like you can discard it and cheat it out for greatly reduced cost the need to have a four power dork in play makes this super unreliable and slow to the point of being more than fair
And, if a current character is threatening the field, you can keep your cards readied so they can't be challenged and protected, thanks to her Ward ability
instead I quit when I stop getting stuck, when I sense Ive seen everything meaningful that a game has to offer
Oh, and General Tazri - the go-to allies leader before Katara came along