Blackjack where doubles and most splits are free.
Doubling hard 9–11 and splitting any pair but tens are free, in exchange for a dealer 22 making every remaining hand a push (your blackjack is still paid). Example: when you double a hard 11, the dealer places a "Free Bet" marker beside your bet. It is paid the same amount when it wins and costs nothing when it loses. Under the published standard rules (6 decks, H17) the house edge is 1.04%, and the key strategy point is to accept every free double and free split.