Cal Petersen made 31 saves for Los Angeles (21-27-7), which has lost four straight (0-3-1).
"The first period, the second period, the third period, execution," Kings coach Todd McLellan said. "A little more consideration for teammates when it comes to effort. I can go on and on. And you can write a book about it. I'm wasting my time here."
Colorado coach Jared Bednar said Jonas Johansson will start in net Thursday.
"He's played well and we haven't played 'Grubi' in any back to backs all year," Bednar said. "We don't want to risk an injury or put him in a position where he does something that he normally doesn't do.
"'JJ's' ready to go tomorrow. If we play the way we can play in front of him, we'll give ourselves a good chance to win. We're going to need to make sure these guys are sharp going into the playoffs."
Joonas Donskoi gave the Avalanche a 1-0 lead at 14:43 of the first period, scoring from the slot on the rebound of Andre Burakovsky's shot on the power play.
Pierre-Edouard Bellemare made it 2-0 at 16:02 when he jammed in a loose puck five-hole on Petersen, and Compher increased the lead to 3-0 at 19:15 with a one-timer from the right face-off circle off a pass from Rantanen.
"I thought we came out with great jump," Landeskog said. "First period, Grubi didn't have much action in his end (three shots). We did a good job of keeping it in the (offensive) zone, turning pucks quickly in the neutral zone and really getting in the hunt. It was nice to get a couple goals midway through the first, and it gave us a little bit of a cushion going into the second. But overall we kept playing well."