Reilly, 23, did not play in the Wild's 4-3 win over the Winnipeg Jets in their home opener Saturday, but did log 14:09 of ice time in the team's season-opening 3-2 loss at the St. Louis Blues last Thursday.
The Detroit Red Wings signed right winger Givani Smith to a three-year entry-level contract.
Smith, 18, was selected by Detroit in the second round (46th overall) of the 2016 NHL draft.
Michalek, 33, has recorded 178 points (42 goals, 136 assists) and 322 penalty minutes in 781 career NHL games with the Coyotes, St. Louis Blues, Pittsburgh Penguins and Minnesota Wild. (Editing by Frank Pingue)