If you are demoing to two players, you can have them play each other. If you are demoing to a single player, you can be their opponent. Both players should be given two packs to open and shuffle together. This gives them tangible proof that they can play using just two packs.
The player(s) should be given a brief overview of the Quick-start Rules and then you should start them playing. It’s easier to hold a player’s attention if they start playing quickly, even if they have to be taught many of the rules as they come up while playing.
The most important things to review with players before they begin are:
1. The action system and how to identify action cards and free cards.
2. The way the different speeds work and how to identify them on cards.
3. The way the Battle Step works.
Once you have covered these things, you can begin playing and explaining the beginning procedures like how many cards to start with, how the mulligan rule works and that the first player starts their turn in the Build Step.