There are 3 distinct discard pile locations on the main game board. Any time a card is discarded, it goes to the appropriate discard pile. If a card says to remove it from the game, do not place it in the discard pile.
Gear Discard Pile
Gear cards are discarded to this pile. Heels can buy the top card of this pile for 2 Heat.
Ring Discard Pile
Ring cards are discarded to this pile. Faces can buy the top card of this pile for 2 Pop.
Superstar Discard Pile
Superstars are discarded to this pile. Stable members can only be chosen from this pile.