Oh so question: is there no offsides during a power play? Also, why are some offsides waved off. I'm so confused.
Hmm anon do you mean offsides or icing?
Offsides is when a player entering the offensive zone (crosses the blue line and leaves the neutral zone) before the puck. Icing is when the puck is shot into the offensive zone and crosses both the center red line and the goal line without being touched by an attacking player.
Offsides is rarely waved off. Sometimes the linesmen miss it until a goal challenge, but if the play is offside, then play is stopped immediately. There’s also delayed offside. If an attacking player is not playing the puck and they’re in the offensive zone before the puck, then they can get back onside and then reenter the offensive zone and the offside is waved off. I don’t see that happen a lot though.
I think you might’ve meant icing, because there is no icing during a penalty kill. If your team is on the power play, you can’t ice the puck. (That almost never happens anyway.) But if your team is on the penalty kill, i.e. you’re short-handed, then you can clear the puck down the ice without it being icing. The one time you can’t do that while short-handed is during a 6-on-5, when the other team pulls their goalie for an extra attacker.
Sometimes icing is waved off because an attacking player gets to it before a defending player. You sometimes see two players racing for the puck; the first one to get to it determines whether there will be icing or not. Say the puck crosses the goal line and the team that iced it gets there first. The linesman will lower their arm and wave off the pending icing call. But if that team dumps the puck and fails to retrieve it before a defending player on the other team gets to it, that’s icing. In the NHL, they don’t always wait for the players to actually touch the puck; if it’s clear which team will get to it first, the call is made earlier. (This is so players don’t go crashing into the boards while racing for the puck.)