The trade of Artturi Lehkonen to Colorado serves a few purposes for them. In the short-term, it gives them someone to slot on the second line in the absence of Gabriel Landeskog. Not that they're in a fight for a playoff spot or anything, but it gives a bit of security in case Calgary makes a push for tops in the Western Conference.
Secondly, it helps lengthen the lineup when Landeskog is back. Lehkonen looks slated to skate on the second line until then but should move to the third line when the captain is healthy. It is a big boost to a third line that Colorado hasn't really had all season long.
As for Lehkonen's fantasy value, I'm not sure how much of a hit it takes, even if he's on the third line. The Avalanche tend to play their top-3 lines heavily and their fourth sparingly. That means he should keep getting around 15 minutes a night, about what he was getting in Montreal, when Landeskog is back. Hopefully, it's status quo as a depth option for fantasy leagues.
An update on the Evgenii Dadonov trade saga:
Not that Cap Friendly is official, but it goes to show how badly this could impact Vegas. This is a problem f