Example 1:

Lover Era cards #1-#5 are out in player's collections. With at least four cards from Lover out on the table, players have the option to start playing songs cards from the Fearless Era. James has #7 - Fearless - which is the first card from the next Era, but can’t play it yet, as single cards need to be added to runs and neither #6 nor #8 is on the table. But Olivia has both #8 and #9, and is able to play the combo on her turn, opening the Fearless Era. On James' next turn, he'll be able to play his #7, building on the run that Olivia started.

Example 2:

Cards #2 - #4 are out in player's collections. Olivia has Fearless Era cards #8 and #9, but can’t play these cards until there are at least for Lover cards on the table. James has #6 (a Lover Era card) and #7 (a Fearless Era card) in his hand. He is able to put down this two-fer, completing the card minimum for Lover and opening Fearless in one play. (Olivia sticks out her tongue at James, and then plays #8-#9).