[quote=@VarionusNW]
Each player has 3, and can hand one to another player to influence their interaction or the duel against them. Pulling a heart of the cards gives it to the GM (or the other player still works potentially?). Then the GM can use these to power up NPCs and monsters in the same way the players can
[/quote]

I like this. 

[@King Cosmos] that is certainly an option