Mixed curling the house. In the 2015-16 season, a new rule called "power play" was added, which each team can exercise in one end per game, only when they have the hammer. Instead of positioning the rock in the house on the center line, it is placed to a position straddling the edge of the eight-foot circle, with the back edge of the stone touching the tee line. The opponent's guard stone is placed in line with the stone in the house and the hack. The power play cannot be used in an extra end. Mixed curling Mixed curling, also known as
Curling four rocks, known as the "three-rock rule" and "four-rock rule" respectively). This rule, a relatively recent addition to curling, was added in response to a strategy of "peeling" opponents' guard stones (knocking them out of play at an angle that caused the shooter's stone to also roll out of play, leaving no stones on the ice). A team in the lead would often employ this strategy during the game. By knocking all stones out, the opponents could at best score one point (if they had the hammer). Alternatively, the team with the hammer could peel rock after rock, which would